malaria
malaria. Other (Public Domain)

Entries

Gale Encyclopedia of Medicine, 3rd ed. Gale Encyclopedia of Alternative MedicineEncyclopedia of Public HealthAnimal Sciences Further reading

NON JS

Malaria

Malaria

Definition

Malaria is a serious infectious disease spread by certain mosquitoes. It is most common in tropical climates. It is characterized by recurrent symptoms of chills, fever, and an enlarged spleen. The disease can be treated with medication, but it often recurs. Malaria is endemic (occurs frequently in a particular locality) in many third world countries. Isolated, small outbreaks sometimes occur within the boundaries of the United States.

Description

Malaria is a growing problem in the United States. Although only about 1400 new cases were reported in the United States and its territories in 2000, many involved returning travelers. In addition, locally transmitted malaria has occurred in California, Florida, Texas, Michigan, New Jersey, and New York City. While malaria can be transmitted in blood, the American blood supply is not screened for malaria. Widespread malarial epidemics are far less likely to occur in the United States, but small localized epidemics could return to the Western world. As of late 2002, primary care physicians are being advised to screen returning travelers with fever for malaria, and a team of public health doctors in Minnesota is recommending screening immigrants, refugees, and international adoptees for the diseaseparticularly those from high-risk areas.

The picture is far more bleak, however, outside the territorial boundaries of the United States. A recent government panel warned that disaster looms over Africa from the disease. Malaria infects between 300 and 500 million people every year in Africa, India, southeast Asia, the Middle East, Oceania, and Central and South America. A 2002 report stated that malaria kills 2.7 million people each year, more than 75 percent of them African children under the age of five. It is predicted that within five years, malaria will kill about as many people as does AIDS. As many as half a billion people worldwide are left with chronic anemia due to malaria infection. In some parts of Africa, people battle up to 40 or more separate episodes of malaria in their lifetimes. The spread of malaria is becoming even more serious as the parasites that cause malaria develop resistance to the drugs used to treat the condition. In late 2002, a group of public health researchers in Thailand reported that a combination treatment regimen involving two drugs known as dihydroartemisinin and azithromycin shows promise in treating multidrug-resistant malaria in southeast Asia.

Causes and symptoms

Human malaria is caused by four different species of a parasite belonging to genus Plasmodium: Plasmodium falciparum (the most deadly), Plasmodium vivax, Plasmodium malariae, and Plasmodium ovale. The last two are fairly uncommon. Many animals can get malaria, but human malaria does not spread to animals. In turn, animal malaria does not spread to humans.

A person gets malaria when bitten by a female mosquito who is looking for a blood meal and is infected with the malaria parasite. The parasites enter the blood stream and travel to the liver, where they multiply. When they re-emerge into the blood, symptoms appear. By the time a patient shows symptoms, the parasites have reproduced very rapidly, clogging blood vessels and rupturing blood cells.

Malaria cannot be casually transmitted directly from one person to another. Instead, a mosquito bites an infected person and then passes the infection on to the next human it bites. It is also possible to spread malaria via contaminated needles or in blood transfusions. This is why all blood donors are carefully screened with questionnaires for possible exposure to malaria.

It is possible to contract malaria in non-endemic areas, although such cases are rare. Nevertheless, at least 89 cases of so-called airport malaria, in which travelers contract malaria while passing through crowded airport terminals, have been identified since 1969.

The amount of time between the mosquito bite and the appearance of symptoms varies, depending on the strain of parasite involved. The incubation period is usually between 8 and 12 days for falciparum malaria, but it can be as long as a month for the other types. Symptoms from some strains of P. vivax may not appear until 8-10 months after the mosquito bite occurred.

The primary symptom of all types of malaria is the "malaria ague" (chills and fever). In most cases, the fever has three stages, beginning with uncontrollable shivering for an hour or two, followed by a rapid spike in temperature (as high as 106°F), which lasts three to six hours. Then, just as suddenly, the patient begins to sweat profusely, which will quickly bring down the fever. Other symptoms may include fatigue, severe headache, or nausea and vomiting. As the sweating subsides, the patient typically feels exhausted and falls asleep. In many cases, this cycle of chills, fever, and sweating occurs every other day, or every third day, and may last for between a week and a month. Those with the chronic form of malaria may have a relapse as long as 50 years after the initial infection.

Falciparum malaria is far more severe than other types of malaria because the parasite attacks all red blood cells, not just the young or old cells, as do other types. It causes the red blood cells to become very "sticky." A patient with this type of malaria can die within hours of the first symptoms. The fever is prolonged. So many red blood cells are destroyed that they block the blood vessels in vital organs (especially the kidneys), and the spleen becomes enlarged. There may be brain damage, leading to coma and convulsions. The kidneys and liver may fail.

Malaria in pregnancy can lead to premature delivery, miscarriage, or stillbirth.

Certain kinds of mosquitoes (called anopheles) can pick up the parasite by biting an infected human. (The more common kinds of mosquitoes in the United States do not transmit the infection.) This is true for as long as that human has parasites in his/her blood. Since strains of malaria do not protect against each other, it is possible to be reinfected with the parasites again and again. It is also possible to develop a chronic infection without developing an effective immune response.

Diagnosis

Malaria is diagnosed by examining blood under a microscope. The parasite can be seen in the blood smears on a slide. These blood smears may need to be repeated over a 72-hour period in order to make a diagnosis. Antibody tests are not usually helpful because many people developed antibodies from past infections, and the tests may not be readily available. A new laser test to detect the presence of malaria parasites in the blood was developed in 2002, but is still under clinical study.

Two new techniques to speed the laboratory diagnosis of malaria show promise as of late 2002. The first is acridine orange (AO), a staining agent that works much faster (3-10 min) than the traditional Giemsa stain (45-60 min) in making the malaria parasites visible under a microscope. The second is a bioassay technique that measures the amount of a substance called histadine-rich protein II (HRP2) in the patient's blood. It allows for a very accurate estimation of parasite development. A dip strip that tests for the presence of HRP2 in blood samples appears to be more accurate in diagnosing malaria than standard microscopic analysis.

Anyone who becomes ill with chills and fever after being in an area where malaria exists must see a doctor and mention their recent travel to endemic areas. A person with the above symptoms who has been in a high-risk area should insist on a blood test for malaria. The doctor may believe the symptoms are just the common flu virus. Malaria is often misdiagnosed by North American doctors who are not used to seeing the disease. Delaying treatment of falciparum malaria can be fatal.

Treatment

Falciparum malaria is a medical emergency that must be treated in the hospital. The type of drugs, the method of giving them, and the length of the treatment depend on where the malaria was contracted and how sick the patient is.

For all strains except falciparum, the treatment for malaria is usually chloroquine (Aralen) by mouth for three days. Those falciparum strains suspected to be resistant to chloroquine are usually treated with a combination of quinine and tetracycline. In countries where quinine resistance is developing, other treatments may include clindamycin (Cleocin), mefloquin (Lariam), or sulfadoxone/pyrimethamine (Fansidar). Most patients receive an antibiotic for seven days. Those who are very ill may need intensive care and intravenous (IV) malaria treatment for the first three days.

Anyone who acquired falciparum malaria in the Dominican Republic, Haiti, Central America west of the Panama Canal, the Middle East, or Egypt can still be cured with chloroquine. Almost all strains of falciparum malaria in Africa, South Africa, India, and southeast Asia are now resistant to chloroquine. In Thailand and Cambodia, there are strains of falciparum malaria that have some resistance to almost all known drugs.

A patient with falciparum malaria needs to be hospitalized and given antimalarial drugs in different combinations and doses depending on the resistance of the strain. The patient may need IV fluids, red blood cell transfusions, kidney dialysis, and assistance breathing.

A drug called primaquine may prevent relapses after recovery from P. vivax or P. ovale. These relapses are caused by a form of the parasite that remains in the liver and can reactivate months or years later.

Another new drug, halofantrine, is available abroad. While it is licensed in the United States, it is not marketed in this country and it is not recommended by the Centers for Disease Control and Prevention in Atlanta.

Alternative treatments

The Chinese herb qiinghaosu (the Western name is artemisinin) has been used in China and southeast Asia to fight severe malaria, and became available in Europe in 1994. Because this treatment often fails, it is usually combined with another antimalarial drug (mefloquine) to boost its effectiveness. It is not available in the United States and other parts of the developed world due to fears of its toxicity, in addition to licensing and other issues.

A Western herb called wormwood (Artemesia annua ) that is taken as a daily dose can be effective against malaria. Protecting the liver with herbs like goldenseal (Hydrastis canadensis ), Chinese goldenthread (Coptis chinensis ), and milk thistle (Silybum marianum ) can be used as preventive treatment. Preventing mosquitoes from biting you while in the tropics is another possible way to avoid malaria.

As of late 2002, researchers are studying a traditional African herbal remedy against malaria. Extracts from Microglossa pyrifolia, a trailing shrub belonging to the daisy family (Asteraceae), show promise in treating drug-resistent strains of P. falciparum.

Prognosis

If treated in the early stages, malaria can be cured. Those who live in areas where malaria is epidemic, however, can contract the disease repeatedly, never fully recovering between bouts of acute infection.

Prevention

Several researchers are currently working on a malarial vaccine, but the complex life cycle of the malaria parasite makes it difficult. A parasite has much more genetic material than a virus or bacterium. For this reason, a successful vaccine has not yet been developed.

Malaria is an especially difficult disease to prevent by vaccination because the parasite goes through several separate stages. One recent promising vaccine appears to have protected up to 60% of people exposed to malaria. This was evident during field trials for the drug that were conducted in South America and Africa. It is not yet commercially available.

The World Health Association (WHO) has been trying to eliminate malaria for the past 30 years by controlling mosquitoes. Their efforts were successful as long as the pesticide DDT killed mosquitoes and antimalarial drugs cured those who were infected. Today, however, the problem has returned a hundred-fold, especially in Africa. Because both the mosquito and parasite are now extremely resistant to the insecticides designed to kill them, governments are now trying to teach people to take antimalarial drugs as a preventive medicine and avoid getting bitten by mosquitoes.

A newer strategy as of late 2002 involves the development of genetically modified non-biting mosquitoes. A research team in Italy is studying the feasibility of this means of controlling malaria.

Travelers to high-risk areas should use insect repellant containing DEET for exposed skin. Because DEET is toxic in large amounts, children should not use a concentration higher than 35%. DEET should not be inhaled. It should not be rubbed onto the eye area, on any broken or irritated skin, or on children's hands. It should be thoroughly washed off after coming indoors.

Those who use the following preventive measures get fewer infections than those who do not:

  • Between dusk and dawn, remain indoors in well-screened areas.
  • Sleep inside pyrethrin or permethrin repellent-soaked mosquito nets.
  • Wear clothes over the entire body.

Anyone visiting endemic areas should take antimalarial drugs starting a day or two before they leave the United States. The drugs used are usually chloroquine or mefloquine. This treatment is continued through at least four weeks after leaving the endemic area. However, even those who take antimalarial drugs and are careful to avoid mosquito bites can still contract malaria.

International travelers are at risk for becoming infected. Most Americans who have acquired falciparum malaria were visiting sub-Saharan Africa; travelers in Asia and South America are less at risk. Travelers who stay in air conditioned hotels on tourist itineraries in urban or resort areas are at lower risk than backpackers, missionaries, and Peace Corps volunteers. Some people in western cities where malaria does not usually exist may acquire the infection from a mosquito carried onto a jet. This is called airport or runway malaria.

KEY TERMS

Arteminisinins A family of antimalarial products derived from an ancient Chinese herbal remedy. Two of the most popular varieties are artemether and artesunate, used mainly in southeast Asia in combination with mefloquine.

Chloroquine An antimalarial drug that was first used in the 1940s, until the first evidence of quinine resistance appeared in the 1960s. It is now ineffective against falciparum malaria almost everywhere. However, because it is inexpensive, it is still the antimalarial drug most widely used in Africa. Native individuals with partial immunity may have better results with chloroquine than a traveler with no previous exposure.

Mefloquine An antimalarial drug that was developed by the United States Army in the early 1980s. Today, malaria resistance to this drug has become a problem in some parts of Asia (especially Thailand and Cambodia).

Mefloquine An antimalarial drug that was developed by the United States Army in the early 1980s. Today, malaria resistance to this drug has become a problem in some parts of Asia (especially Thailand and Cambodia).

Quinine One of the first treatments for malaria, quinine is a natural product made from the bark of the Cinchona tree. It was popular until being superseded by the development of chloroquine in the 1940s. In the wake of widespread chloroquine resistance, however, it has become popular again. Quinine, or its close relative quinidine, can be given intravenously to treat severe Falciparum malaria.

Sulfadoxone/pyrimethamine (Fansidar) An antimalarial drug developed in the 1960s. It is the first drug tried in some parts of the world where chloroquine resistance is widespread. It has been associated with severe allergic reactions due to its sulfa component.

Resources

BOOKS

Beers, Mark H., MD, and Robert Berkow, MD, editors. "Extraintestinal Protozoa: Malaria." Section 13, Chapter 161. In The Merck Manual of Diagnosis and Therapy. Whitehouse Station, NJ: Merck Research Laboratories, 2004.

PERIODICALS

Causer, Louise M, et al. "Malaria SurveillanceUnited States, 2000." Morbidity and Mortality Weekly Report July 12, 2002: 9-15. Abstract.

Coluzzi, M., and C. Costantini. "An Alternative Focus in Strategic Research on Disease Vectors: The Potential of Genetically Modified Non-Biting Mosquitoes." Parassitologia 44 (December 2002): 131-135.

"Combination Approach Results in Significant Drop in Malaria Rates in Viet Nam." TB & Outbreaks Week Abstract (September 24, 2002): 17.

Devi, G., V. A. Indumathi, D. Sridharan, et al. "Evaluation of ParaHITf Strip Test for Diagnosis of Malarial Infection." Indian Journal of Medical Science 56 (October 2002): 489-494.

Keiser, J., J. Utzinger, Z. Premji, et al. "Acridine Orange for Malaria Diagnosis: Its Diagnostic Performance, Its Promotion and Implementation in Tanzania, and the Implications for Malaria Control." Annals of Tropical Medicine and Parasitology 96 (October 2002): 643-654.

Kohler, I., K. Jenett-Siems, C. Kraft, et al. "Herbal Remedies Traditionally Used Against Malaria in Ghana: Bioassay-Guided Fractionation of Microglossa pyrifolia (Asteraceae)." Zur Naturforschung 57 (November-December 2002): 1022-1027.

Krudsood, S., K. Buchachart, K. Chalermrut, et al. "A Comparative Clinical Trial of Combinations of Dihydroartemisinin Plus Azithromycin and Dihydroartemisinin Plus Mefloquine for Treatment of Multidrug-Resistant Falciparum Malaria." Southeast Asian Journal of Tropical Medicine and Public Health 33 (September 2002): 525-531.

"Laser-based Malaria Test could be Valuable." Medical Devices & Surgical Technology Week September 22, 2002: 4.

McClellan, S. L. "Evaluation of Fever in the Returned Traveler." Primary Care 29 (December 2002): 947-969.

"Multilateral Initiative on Malaria to Move to Sweden." TB & Outbreaks Week September 24, 2002: 17.

Noedl, H., C. Wongsrichanalai, R. S. Miller, et al. "Plasmodium falciparum: Effect of Anti-Malarial Drugs on the Production and Secretion Characteristics of Histidine-Rich Protein II." Experimental Parasitology 102 (November-December 2002): 157-163.

"Promising Vaccine May Provide Long-Lasting Protection." Medical Letter on the CDC & FDA September 15, 2002: 14.

Stauffer, W. M., D. Kamat, and P. F. Walker. "Screening of International Immigrants, Refugees, and Adoptees." Primary Care 29 (December 2002): 879-905.

Thang, H. D., R. M. Elsas, and J. Veenstra. "Airport Malaria: Report of a Case and a Brief Review of the Literature." Netherlands Journal of Medicine 60 (December 2002): 441-443.

ORGANIZATIONS

Centers for Disease Control Malaria Hotline. (770) 332-4555.

Centers for Disease Control Travelers Hotline. (770) 332-4559.

OTHER

Malaria Foundation Page. http://www.malaria.org.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

Turkington, Carol; Frey, Rebecca. "Malaria." Gale Encyclopedia of Medicine, 3rd ed.. 2006. Encyclopedia.com. 27 Jun. 2016 <http://www.encyclopedia.com>.

Turkington, Carol; Frey, Rebecca. "Malaria." Gale Encyclopedia of Medicine, 3rd ed.. 2006. Encyclopedia.com. (June 27, 2016). http://www.encyclopedia.com/doc/1G2-3451601011.html

Turkington, Carol; Frey, Rebecca. "Malaria." Gale Encyclopedia of Medicine, 3rd ed.. 2006. Retrieved June 27, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3451601011.html

Malaria

Malaria

Definition

Malaria is a serious infectious disease spread by certain mosquitoes. It is most common in tropical climates. It is characterized by recurrent symptoms of chills, fever , and an enlarged spleen. The disease can be treated with medication, but it often recurs. Malaria is endemic (occurs frequently in a particular locality) in many third world countries. Isolated, small outbreaks sometimes occur within the boundaries of the United States, with most of the cases reported as having been imported from other locations.

Description

Malaria is a growing problem in the United States. Although only about 1400 new cases were reported in the United States and its territories in 2000, many involved returning travelers. In addition, locally transmitted malaria has occurred in California, Florida, Texas, Michigan, New Jersey, and New York City. While malaria can be transmitted in blood, the American blood supply is not screened for malaria. Widespread malarial epidemics are far less likely to occur in the United States, but small localized epidemics could return to the Western world. As of late 2002, primary care physicians are being advised to screen returning travelers with fever for malaria, and a team of public health doctors in Minnesota is recommending screening immigrants, refugees, and international adoptees for the diseaseparticularly those from high-risk areas.

The picture is far more bleak, however, outside the territorial boundaries of the United States. A recent government panel warned that disaster looms over Africa from the disease. Malaria infects between 300 and 500 million people every year in Africa, India, southeast Asia, the Middle East, Oceania, and Central and South America. A 2002 report stated that malaria kills 2.7 million people each year, more than 75 percent of them African children under the age of five. It is predicted that within five years, malaria will kill about as many people as does AIDS . As many as half a billion people worldwide are left with chronic anemia due to malaria infection. In some parts of Africa, people battle up to 40 or more separate episodes of malaria in their lifetimes. The spread of malaria is becoming even more serious as the parasites that cause malaria develop resistance to the drugs used to treat the condition. In late 2002, a group of public health researchers in Thailand reported that a combination treatment regimen involving two drugs known as dihydroartemisinin and azithromycin shows promises in treating multidrug-resistant malaria in southeast Asia.

Causes & symptoms

Human malaria is caused by four different species of a parasite belonging to genus Plasmodium : Plasmodium falciparum (the most deadly), Plasmodium vivax, Plasmodium malariae, and Plasmodium ovale. The last two are fairly uncommon. Many animals can get malaria, but human malaria does not spread to animals. In turn, animal malaria does not spread to humans.

A person gets malaria when bitten by a female mosquito seeking a blood meal that is infected with the malaria parasite. The parasites enter the blood stream and travel to the liver, where they multiply. When they reemerge into the blood, symptoms appear. By the time a patient shows symptoms, the parasites have reproduced very rapidly, clogging blood vessels and rupturing blood cells.

Malaria cannot be casually transmitted directly from one person to another. Instead, a mosquito bites an infected person and then passes the infection on to the next human it bites. It is also possible to spread malaria via contaminated needles or in blood transfusions. This is why all blood donors are carefully screened with questionnaires for possible exposure to malaria.

It is possible to contract malaria in non-endemic areas, although such cases are rare. Nevertheless, at least 89 cases of so-called airport malaria, in which travelers contract malaria while passing through crowded airport terminals, have been identified since 1969.

The amount of time between the mosquito bite and the appearance of symptoms varies, depending on the strain of parasite involved. The incubation period is usually between eight and 12 days for falciparum malaria, but it can be as long as a month for the other types. Symptoms from some strains of P. vivax may not appear until eight to 10 months after the mosquito bite occurred.

The primary symptom of all types of malaria is the "malaria ague" (chills and fever), which corresponds to the "birth" of the new generation of the parasite. In most cases, the fever has three stages, beginning with uncontrollable shivering for an hour or two, followed by a rapid spike in temperature (as high as 106°F [41.4°C]), which lasts three to six hours. Then, just as suddenly, the patient begins to sweat profusely, which will quickly bring down the fever. Other symptoms may include fatigue , severe headache , or nausea and vomiting . As the sweating subsides, the patient typically feels exhausted and falls asleep. In many cases, this cycle of chills, fever, and sweating occurs every other day, or every third day, and may last for between a week and a month. Those with the chronic form of malaria may have a relapse as long as 50 years after the initial infection.

Falciparum malaria is far more severe than other types of malaria because the parasite attacks all red blood cells, not just the young or old cells, as do other types. It causes the red blood cells to become very "sticky." A patient with this type of malaria can die within hours of the first symptoms. The fever is prolonged. So many red blood cells are destroyed that they block the blood vessels in vital organs (especially the brain and kidneys), and the spleen becomes enlarged. There may be brain damage, leading to coma and convulsions. The kidneys and liver may fail.

Malaria in pregnancy can lead to premature delivery, miscarriage, or stillbirth.

Certain kinds of mosquitoes belonging to the genus Anopheles can pick up the parasite by biting an infected human. (The more common kinds of mosquitoes in the United States do not transmit the infection.) This is true for as long as that human has parasites in his/her blood. Since strains of malaria do not protect against each other, it is possible to be reinfected with the parasites again and again. It is also possible to develop a chronic infection without developing an effective immune response.

Diagnosis

Malaria is diagnosed by examining blood under a microscope. The parasite can be seen in the blood smears on a slide. These blood smears may need to be repeated over a 72-hour period in order to make a diagnosis. Antibody tests are not usually helpful because many people developed antibodies from past infections , and the tests may not be readily available. A new laser test to detect the presence of malaria parasites in the blood was developed in 2002, but is still under clinical study.

Two new techniques to speed the laboratory diagnosis of malaria show promise as of late 2002. The first is acridine orange (AO), a staining agent that works much faster (310 minutes) than the traditional Giemsa stain (4560 min) in making the malaria parasites visible under a microscope. The second is a bioassay technique that measures the amount of a substance called hista-dine-rich protein II (HRP2) in the patient's blood. It allows for a very accurate estimation of parasite development. A dip strip that tests for the presence of HRP2 in blood samples appears to be more accurate in diagnosing malaria than standard microscopic analysis.

Anyone who becomes ill with chills and fever after being in an area where malaria exists must see a doctor and mention their recent travel to endemic areas. A person with the above symptoms who has been in a high-risk area should insist on a blood test for malaria. The doctor may believe the symptoms are just the common flu virus. Malaria is often misdiagnosed by North American doctors who are not used to seeing the disease. Delaying treatment of falciparum malaria can be fatal.

Treatment

Traditional Chinese medicine

The Chinese herb qiinghaosu (the Western name is artemisinin) has been used in China and southeast Asia to fight severe malaria, and became available in Europe in 1994. It is usually combined with another antimalarial drug (mefloquine) to prevent relapse and drug resistance. It is not available in the United States and other parts of the developed world due to fears of its toxicity, in addition to licensing and other issues.

Western herbal medicine

A Western herb called wormwood (Artemesia annua ) that is taken as a daily dose may be effective against malaria. Protecting the liver with herbs like goldenseal (Hydrastis canadensis ), Chinese goldenthread (Coptis chinensis ), and milk thistle (Silybum marianum ) can be used as preventive treatment. These herbs should only be used as complementary to conventional treatment and not to replace it. Patients should consult their doctors before trying any of these medications.

Traditional African herbal medicine

As of late 2002, researchers are studying a traditional African herbal remedy against malaria. Extracts from Microglossa pyrifolia, a trailing shrub belonging to the daisy family (Asteraceae), show promise in treating drug-resistent strains of P. falciparum.

Allopathic treatment

Falciparum malaria is a medical emergency that must be treated in the hospital. The type of drugs, the method of giving them, and the length of the treatment depend on where the malaria was contracted and the severity of the patientís illness.

For all strains except falciparum, the treatment for malaria is usually chloroquine (Aralen) by mouth for three days. Those falciparum strains suspected to be resistant to chloroquine are usually treated with a combination of quinine and tetracycline. In countries where quinine resistance is developing, other treatments may include clindamycin (Cleocin), mefloquin (Lariam), or sulfadoxone/pyrimethamine (Fansidar). Most patients receive an antibiotic for seven days. Those who are very ill may need intensive care and intravenous (IV) malaria treatment for the first three days.

A patient with falciparum malaria needs to be hospitalized and given antimalarial drugs in different combinations and doses depending on the resistance of the strain. The patient may need IV fluids, red blood cell transfusions, kidney dialysis, and assistance breathing.

A drug called primaquine may prevent relapses after recovery from P. vivax or P. ovale. These relapses are caused by a form of the parasite that remains in the liver and can reactivate months or years later.

Another new drug, halofantrine, is available abroad. While it is licensed in the United States, it is not marketed in this country and it is not recommended by the Centers for Disease Control and Prevention in Atlanta.

Expected results

If treated in the early stages, malaria can be cured. Those who live in areas where malaria is epidemic, however, can contract the disease repeatedly, never fully recovering between bouts of acute infection.

Prevention

Preventing mosquito bites while in the tropics is one possible way to avoid malaria. Several researchers are currently working on a malarial vaccine, but the complex life cycle of the malaria parasite makes it difficult. A parasite has much more genetic material than a virus or bacterium. For this reason, a successful vaccine has not yet been developed. A new longer-lasting vaccine shows promise, attacking the toxin of the parasite and therefore lasts longer than the few weeks of those vaccines currently used for malaria prevention. However, as of late 2002, the vaccine had been tested only in animals, not in humans, and could be several years from use.

A newer strategy involves the development of genetically modified non-biting mosquitoes. A research team in Italy is studying the feasibility of this means of controlling malaria.

Malaria is an especially difficult disease to prevent by vaccination because the parasite goes through several life stages. One recent, promising vaccine appears to have protected up to 60% of people exposed to malaria. This was evident during field trials for the drug that were conducted in South America and Africa. It is not yet commercially available.

The World Health Organization has been trying to eliminate malaria for the past 30 years by controlling mosquitoes. Their efforts were successful as long as the pesticide DDT killed mosquitoes and antimalarial drugs cured those who were infected. Today, however, the problem has returned a hundredfold, especially in Africa. Because both the mosquito and parasite are now extremely resistant to the insecticides designed to kill them, governments are now trying to teach people to take antimalarial drugs as a preventive medicine and avoid getting bitten by mosquitoes.

Travelers to high-risk areas should use insect repellant containing DEET for exposed skin. Because DEET is toxic in large amounts, children should not use a concentration higher than 35%. DEET should not be inhaled. It should not be rubbed onto the eye area, on any broken or irritated skin, or on children's hands. It should be thoroughly washed off after coming indoors.

Those who use the following preventive measures get fewer infections than those who do not:

  • Between dusk and dawn, remaining indoors in well-screened areas.
  • Sleep inside pyrethrin or permethrin repellent-soaked mosquito nets.
  • Wearing clothes over the entire body.

Anyone visiting areas where malaria is endemic should take antimalarial drugs starting one week before they leave the United States. The drugs used are usually chloroquine or mefloquine. This treatment is continued through at least four weeks after leaving the endemic area. However, even those who take antimalarial drugs and are careful to avoid mosquito bites can still contract malaria.

International travelers are at risk for becoming infected. Most Americans who have acquired falciparum malaria were visiting sub-Saharan Africa; travelers in Asia and South America are less at risk. Travelers who stay in air conditioned hotels on tourist itineraries in urban or resort areas are at lower risk than those who travel outside these areas, such as backpackers, missionaries, and Peace Corps volunteers. Some people in Western cities where malaria does not usually exist may acquire the infection from a mosquito carried onto a jet. This is called airport or runway malaria.

A 2002 report showed how efforts in a Vietnamese village to approach prevention from multiple angles resulted in a significant drop in malaria cases. Health workers distributed bednets treated with permethrin throughout the village and also made sure they were resprayed every six months. They also worked to ensure early diagnosis, early treatment, and annual surveys of villagers to bring malaria under control.

Resources

BOOKS

Desowitz, Robert S. The Malaria Capers: More Tales of Parasites and People, Research and Reality. New York: W.W. Norton, 1993.

"Extraintestinal Protozoa: Malaria." Section 13, Chapter 161 in The Merck Manual of Diagnosis and Therapy, edited by Mark H. Beers, MD, and Robert Berkow, MD. White-house Station, NJ: Merck Research Laboratories, 1999.

Stoffman, Phyllis. The Family Guide to Preventing and Treating 100 Infectious Illnesses. New York: John Wiley & Sons, 1995.

PERIODICALS

Ambroise-Thomas P. "[Curent Data on Major Novel Anti-malarial Drugs: Artemisinin (qinghaosu) derivatives]". [Article in French]. Bulletin of the Academy of National Medicine 183, no.4 (1999): 797780. Abstract.

Causer, Louise M, et al. "Malaria SurveillanceUnited States, 2000". Morbidity and Mortality Weekly Report (July 12, 2002): 915. Abstract.

Coluzzi, M., and C. Costantini. "An Alternative Focus in Strategic Research on Disease Vectors: The Potential of Genetically Modified Non-Biting Mosquitoes." Parassitologia 44 (December 2002): 131135.

"Combination Approach Results in Significant Drop in Malaria Rates in Viet Nam." TB & Outbreaks Week (September 24, 2002): 17. Abstract.

Devi, G., V. A. Indumathi, D. Sridharan, et al. "Evaluation of ParaHITf Strip Test for Diagnosis of Malarial Infection." Indian Journal of Medical Science 56 (October 2002): 489494.

Keiser, J., J. Utzinger, Z. Premji, et al. "Acridine Orange for Malaria Diagnosis: Its Diagnostic Performance, Its Promotion and Implementation in Tanzania, and the Implications for Malaria Control." Annals of Tropical Medicine and Parasitology 96 (October 2002): 643654.

Kohler, I., K. Jenett-Siems, C. Kraft, et al. "Herbal Remedies Traditionally Used Against Malaria in Ghana: Bioassay-Guided Fractionation of Microglossa pyrifolia (Asteraceae)." Zur Naturforschung 57 (November-December 2002): 10221027.

Krudsood, S., K. Buchachart, K. Chalermrut, et al. "A Comparative Clinical Trial of Combinations of Dihydroartemisinin Plus Azithromycin and Dihydroartemisinin Plus Mefloquine for Treatment of Multidrug-Resistant Falciparum Malaria." Southeast Asian Journal of Tropical Medicine and Public Health 33 (September 2002): 525531.

"Laser-based Malaria Test could be Valuable." Medical Devices & Surgical Technology Week (September 22, 2002):4.

Mack, Alison. "Collaborative Efforts Under Way to Combat Malaria." The Scientist 10 (May 12, 1997): 1, 6.

McClellan, S. L. "Evaluation of Fever in the Returned Traveler." Primary Care 29 (December 2002): 947969.

"Multilateral Initiative on Malaria to Move to Sweden." TB & Outbreaks Week (September 24, 2002): 17.

Noedl, H., C. Wongsrichanalai, R. S. Miller, et al. "Plasmodium falciparum : Effect of Anti-Malarial Drugs on the Production and Secretion Characteristics of Histidine-Rich Protein II." Experimental Parasitology 102 (November-December 2002): 157163.

"Promising Vaccine May Provide Long-Lasting Protection." Medical Letter on the CDC & FDA (September 15, 2002): 14.

Stauffer, W. M., D. Kamat, and P. F. Walker. "Screening of International Immigrants, Refugees, and Adoptees." Primary Care 29 (December 2002): 879905.

Thang, H. D., R. M. Elsas, and J. Veenstra. "Airport Malaria: Report of a Case and a Brief Review of the Literature." Netherlands Journal of Medicine 60 (December 2002): 441443.

ORGANIZATIONS

Centers for Disease Control Malaria Hotline. (770) 3324555.

Centers for Disease Control Travelers Hotline. (770) 3324559.

OTHER

Malaria Foundation. http://www.malaria.org.

Mai Tran

Teresa G. Odle

Rebecca J. Frey, PhD

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

Tran, Mai; Odle, Teresa; Frey, Rebecca. "Malaria." Gale Encyclopedia of Alternative Medicine. 2005. Encyclopedia.com. 27 Jun. 2016 <http://www.encyclopedia.com>.

Tran, Mai; Odle, Teresa; Frey, Rebecca. "Malaria." Gale Encyclopedia of Alternative Medicine. 2005. Encyclopedia.com. (June 27, 2016). http://www.encyclopedia.com/doc/1G2-3435100507.html

Tran, Mai; Odle, Teresa; Frey, Rebecca. "Malaria." Gale Encyclopedia of Alternative Medicine. 2005. Retrieved June 27, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3435100507.html

Malaria

MALARIA

Malaria is the most clinically important parasitic disease worldwide. It kills as many as 2.7 million people annually. The human suffering and economic costs are enormous. Although malaria has been eradicated from temperate zones, it continues to pose a major public health threat to more than forty percent of the world's population.

EPIDEMIOLOGY AND TRANSMISSION

Currently, malaria occurs in one hundred countries and territories inhabited by a total of 2.4 billion people (see Figure 1). The World Health Organization estimates that there are 300 million to 500 million clinical cases annually, resulting in approximately 1.5 million to 2.7 million deaths. Ninety percent of the deaths are in children under five years of age living in sub-Saharan Africa. Other risk groups include pregnant women, internally displaced persons and refugees, and international travelers.

Malaria transmission occurs by the bite of an infective female Anopheles sp. mosquito. Although most cases are transmitted by mosquito, the infection can be passed from mother to the unborn child, or through contaminated blood products, needle sharing, or organ transplantation.

AGENT AND LIFE CYCLE

Human malaria infection is caused by one or more of four species of the intracellular parasite of the genus plasmodium. Plasmodium falciparum, P. vivax, P. ovale, and P. malariae differ in geographic distribution, microscopic appearance, clinical characteristics, and potential for conferring immunity in the host. Although P. vivax is the most common form of malaria worldwide, P. falciparum is the most severe, contributing to most of the morbidity and mortality.

The life cycle of the four species of human malaria consists of two phases: the sexual (sporogony) and asexual phases (schizogony; see Figure 2). Schizogony begins when an infective female anopheline mosquito injects sporozoites into the human host while taking a blood meal. The sporozoite stage of the parasite disappears from circulation within thirty minutes. Those avoiding the host immune system invade the liver and undergo development and multiplication to form schizonts. Over the next five to fifteen days, the schizonts mature, rupture the liver cell, and invade the circulation as merozoites. These merozoites bind to the red blood cell wall. They then penetrate the red blood cell, where they develop as ring forms and grow into trophozoites. Further division creates red blood cell merozoites which form a mature schizont. The blood cell swells and ruptures, releasing merozoites that go on to invade other red blood cells. Clinical symptoms result when the blood cell ruptures and releases cellular debris from infected cells into the bloodstream. The host response to these toxins produces the

Figure 1

classic paroxysms of fever and chills, which are closely timed with the cycles of red blood cell schizogony. The timing of the blood cell phase differs depending on the species of the parasite. P. vivax and P. ovale classically have cycles of forty-eight hours, P. malariae seventy-two hours, and P. falciparum forty-eight hours, although this may vary.

After a period of time, some of the merozoites develop into male and female sexual forms called gametocytes. The gametocytes are ingested by the female anopheline mosquito during a blood meal. Inside the mosquito's stomach, the male and female gametocyte fuse to form a zygote, which quickly becomes a mobile oökinete, which penetrates the stomach wall to form an oöcyst. The oöcyst then bursts, releasing sporozoites that migrate to the salivary glands, ready to be injected into a human host, thus completing the cycle. The parasite generally develops within the mosquito (sporogony) in nine to twelve days, but this time varies according to parasite species and external temperature.

P. vivax and P. ovale differ from the other two species in that some hepatic trophozoites, called hypnozoites, may remain dormant and persist in the liver for months to up to four years. Periodic release of merozoites formed from these hypnozoites can produce recurrent parasitemia and clinical symptoms. Recurrent parasitemia can also occur with P. falciparum and P. malariae, although these species do not form hypnozoites. Infection with these parasites may remain in the blood at subclinical levels because of either the host immune system or use of antimalarial drugs

Figure 2

that do not completely clear the blood-stage parasites. The level of parasitemia can increase weeks to months later, giving rise to another clinical attack. While P. falciparum rarely returns more than several months after the initial infection, P. malariae may become active again up to forty years after the infection.

CLINICAL DISEASE AND DIAGNOSIS

The clinical presentation of malaria is very nonspecific. The degree of natural and acquired immunity of the patient can influence the clinical course dramatically. Classic symptoms among nonimmune persons include fever, chills, sweats, body aches, headache, decreased appetite, nausea, vomiting, and diarrhea. Signs of malaria infection may include an enlarged liver and spleen, anemia, jaundice, low blood pressure, fast heart rate, and decreases in the number of white blood cells and platelets. Children may also show fretfulness, unusual crying, and sleep disturbances. The hallmark of malaria is the paroxysms (attacks) of these symptoms, which recur with predictable periodicity. P. vivax and P. ovale malaria classically cause symptoms every forty-eight hours, P. malariae every seventy-two hours. P. falciparum features irregular patterns. The presentation of these classic attacks is highly variable and may not occur at all early in the disease or in partially immune persons.

Life-threatening disease generally occurs only with P. falciparum infections and can progress from uncomplicated malaria within hours. Neurologic manifestations are the most common presentation of severe disease, often appearing as altered mental status, drowsiness, coma, or convulsions. Other important severe clinical conditions include renal failure, pulmonary distress, severe anemia, low blood sugar, and shock.

Malaria in pregnancy can have devastating effects, especially when caused by P. falciparum. In nonimmune pregnant women, malaria infections can lead to increased risk of maternal and fetal death. Among semi-immune pregnant women, low birth weight due to placental parasitemia represents the greatest risk factor for neonatal death.

Due to the nonspecific nature of malaria symptoms, the diagnosis cannot be made based on clinical signs and symptoms alone. Laboratory diagnostic tests must be performed on any patient suspected of having a malaria infection. The standard for diagnosing malaria is the microscopic visualization of parasites in red blood cells on Giemsa-stained thick and thin smears. Advantages of microscopy include high sensitivity and specificity among properly trained and supervised technicians. Microscopy also offers the ability to identify the infecting species and quantify the level of parasitemia. Immunochromatographic rapid diagnostic tests have been developed that may detect P. falciparum and nonP. falciparum infections. These require no special equipment and are relatively easy to use. The determination of parasite density is not possible with these dipsticks. Other less common methods used for diagnosing malaria infections include serologic tests using an enzyme-linked immunosorbent assay, radioimmunoassay techniques, and polymerase chain reaction.

TREATMENT

To decrease morbidity and mortality from malaria infections, early diagnosis and prompt treatment with an efficacious drug are important. Unfortunately, due to the increasing spread and intensification of drug resistance, there is a limited number of drugs available to prevent and treat malaria.

Chloroquine has long been the mainstay first-line therapy for uncomplicated P. falciparum infection used by malaria control programs; however, resistance to it now exists in most parts of the world. Sulfadoxine-pyrimethamine (SP) has replaced chloroquine in many countries. Resistance to SP has developed in Southeast Asia, parts of South America, and now in certain sites in sub-Saharan Africa. Other drugs commonly used for falciparum infections include quinine, quinidine, amodiaquine, mefloquine, halofantrine, artemisinin compounds, atovaquone, tetracycline, and clindamycin.

Chloroquine is the main drug used for infections with P. vivax, P. ovale, and P. malariae ; however, there are reports of chloroquine-resistant P. vivax in parts of Oceania. Primaquine is used to eliminate the hypnozoites in P. vivax and P. ovale infections.

CONTROL MEASURES

Four basic elements of an effective malaria control program include case management, selective and sustainable preventive measures, early detection of epidemics, and the strengthening of local capacity. Appropriate case management is imperative to malaria control programs. It consists of accurate diagnosis followed by rapid, effective treatment. The detection of malaria in children and pregnant women is especially important. Knowledge of mosquito behavior and relevant environmental, social, and economic features is extremely important for malaria prevention programs. These programs often consist of personal protection (e.g., repellents, insecticide-impregnated bednets), chemoprophylaxis (chemical agent to prevent malaria) for travelers or other high-risk persons, and selective mosquito control (e.g., insecticides, larvicides, environmental management). Malaria epidemics can occur when a community with little or no immunity moves into an area of intense malaria transmission. Epidemics often take place in times of socio-political instability (e.g., complex humanitarian emergencies). These may result in high numbers of deaths. Finally, to be able to control transmission, malaria-endemic countries need to integrate control efforts into the national health plan, strengthen in-country scientific capacity to perform malaria research, and mobilize community support for intervention programs.

John R. MacArthur

S. Patrick Kachur

(see also: Communicable Disease Control; Vector-Borne Diseases )

Bibliography

Bloland, P. B.; Lacritz, E. M.; Kazembe, P. N. et al. (1993). "Beyond Chloroquine: Implications of Drug Resistance for Evaluating Malaria Therapy Efficacy and Treatment Policy in Africa." Journal of Infectious Diseases 167:932937.

Bruce-Chwatt, L. J. (1986). Chemotherapy of Malaria. Geneva: World Health Organization.

Gilles, H. M., and Warrell, D. A. (1993). Bruce-Chwatt's Essential Malariology, 3rd edition. London: Arnold.

Kachur, S. P., and Bloland, P. B. (1998). "Malaria." In Maxcy-Rosenau-Last's Public Health and Preventive Medicine, 14th edition, ed. R. B. Wallace. Stamford, CT: Appleton & Lange.

MacArthur, J. R.; Williams, H. A.; and Bloland, P. B. (2000). "Malaria in Complex Humanitarian Emergencies." Refuge 18(5):411.

Nwanyanwu, O. C.; Ziba, C.; MacHeso, A.; and Kazembe, P. (2000). "Efficacy of Sulphadoxine-pyrimethamine for Acute Uncomplicated Malaria Due to Plasmodium falciparum in Malawian Children under Five Years Old." Tropical Medicine and International Health 5:355358.

White, N. J. (1996). "The Treatment of Malaria." New England Journal of Medicine 335:800806.

World Health Organization (1993). A Global Strategy for Malaria Control. Geneva: Author.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

Macarthur, John R.; Kachur, S. Patrick. "Malaria." Encyclopedia of Public Health. 2002. Encyclopedia.com. 27 Jun. 2016 <http://www.encyclopedia.com>.

Macarthur, John R.; Kachur, S. Patrick. "Malaria." Encyclopedia of Public Health. 2002. Encyclopedia.com. (June 27, 2016). http://www.encyclopedia.com/doc/1G2-3404000511.html

Macarthur, John R.; Kachur, S. Patrick. "Malaria." Encyclopedia of Public Health. 2002. Retrieved June 27, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3404000511.html

Malaria

Malaria

Malaria is one of the oldest known infections. It is also the world's most deadly tropical parasitic disease. It kills more people than any other communicable disease except tuberculosis. The disease was first described in ancient Sanskrit and Chinese documents. Hippocrates also described the disease in his writings. It is believed that the army of Alexander the Great was wiped out by the disease during its march across India.

Malaria is thought to have been introduced into the United States by European colonists and African slaves in the sixteenth and seventeenth centuries. It is now endemic in ninety-two countries worldwide. With approximately 41 percent of the world's population at risk, the disease poses a serious health threat globally. As many as two million people die annually; half of the deaths occur in children under five years of age. According to the World Health Organization, this amounts to one child dying every thirty seconds.

Malaria is characterized by both acute and relapsing infection in humans. Hallmark symptoms include periodic episodes of chills and fever, spleen enlargement, and anemia . The disease is caused by microscopic onecelled organisms called sporozoa , which belong to the genus Plasmodium. These parasites are transmitted to humans by several species of anopheles mosquitoes. Malaria is also found in apes, monkeys, birds, bats, reptiles, and rodents. While humans can be infected only by Anopheles mosquitoes, birds and other animals are known to have become ill after being bitten by mosquitoes from the genus Culex.

Four species of Plasmodium are known to cause human malaria: P. falciparum, P. vivax, P. malariae, and P. ovale. Diagnosis can be determined by a blood smear. The most common type, P. falciparum, requires relatively high environmental temperatures for development and is usually found in tropical areas such as western Africa. P. vivax malaria accounts for 43 percent of all cases and is widespread globally. It is known to occur even in cold-winter areas of Korea, Manchuria, and south Russia. The less common P. malariae malaria occurs in about 7 percent of all cases and is confined to the Mediterranean, while P. ovale malaria is rather rare and isolated within a small area of eastern Africa and the islands of the western Pacific.

Malarial attacks typically last four to ten hours during which a person experiences successive stages of chills, high fever, severe headache, and then profuse sweating. Between attacks, body temperature may be normal. The intervals between attacks are usually either forty-eight hours or seventy-two hours. The first attack typically occurs seven to nine days after a person is bitten by a disease-carrying mosquito.

Mosquito Transmission

Though malaria can occur in temperate regions, it is most common in the tropics and subtropics, where climatic conditions favor mosquito development. Mosquitoes lay their eggs in water where larvae mature and hatch into flying adults. Newly hatched female mosquitoes are especially bloodthirsty and require a blood meal to produce fertile eggs. When these mosquitoes bite a human who is already infected, they ingest the malarial parasite and the disease transmission cycle begins.

The life cycle of the Plasmodium starts in the stomach of the female mosquito. The organism's double life cycle has two phasesa sexual reproductive cycle and an asexual reproductive cycle. While the parasite is in its asexual, free-swimming stage, it is known as a sporozoite . When an infected mosquito bites, the sporozoite is injected along with saliva into the human bloodstream.

Once inside the bloodstream, the sporozoite enters a red blood cell. Inside the red blood cell, it changes shape and divides into smaller forms called merozoites . The red blood cell containing these merozoites ruptures, releasing them into the blood. The merozoites infect other red blood cells, and the life cycle is repeated. The rupturing of red blood cells causes the symptoms of fever and chills.

A mosquito biting an infected host at this stage can ingest merozoites. If this happens, the merozoites enter the mosquito's stomach and become male and female gametocytes . This kicks off a sexual reproductive life cycle where the separate male and female gametocytes unite together to form a single-celled zygote . This zygote grows to become an oocyst or large egglike sac, which eventually divides, releasing a multitude of asexual, freeswimming sporozoites.

These sporozoites move to the mosquito's head and salivary glands from which they can be injected into a human during the mosquito's next bite. This asexual cycle is repeated. During the asexual life cycle, the parasites grow and divide synchronously. The resulting merozoites produce the regularly occurring fever and chill attacks that are typical of malaria.

Early Cases and Treatments

The first documented treatment of the disease occurred in 1630 when "Jesuit's bark," from a cinchona tree, was used to ease the fever of a Spanish magistrate in Peru. Amazingly, the magistrate recovered and eventually the substance quinine was isolated from the bark and processed commercially as a treatment. The Cinchona genus includes about forty species of plants, mostly trees, native to the Andes of South America. Certain species are also known to grow in India and Sri Lanka.

In the 1940s, the antimalarial drug chloroquine was introduced as an effective additional treatment. Chloroquine is a member of an important series of chemically related antimalarial agents, the quinoline derivatives. A global eradication program was initiated in the 1950s and 1960s by the World Health Organization (WHO), in Geneva, Switzerland, which led to a significant decrease in malaria cases in Asia and South America.

Drug Resistant Strains and Reemergence of Disease

Drug resistant strains of malaria began to emerge in the 1970s, making the disease harder to control. During the 1990s the prevalence of malaria escalated at an alarming rate, especially in Africa where control efforts have typically been piecemeal and uncoordinated. Additionally, the phenomenon of "airport malaria," or the importing of malaria by international travelers, is becoming commonplace. Persons who are not normally exposed to this mosquito in its natural habitat can acquire "airport malaria" through the bite of an infected mosquito that has traveled far from its home.

In one study, random searches of airplanes at Gatwick Airport in London found dozens of airplanes from tropical countries containing mosquitoes. After a mosquito leaves an aircraft, it may survive long enough to take a blood meal and transmit the disease, usually in the vicinity of the airport. Incidents of malaria transmitted this way are expected to become more common, since airport travel has increased by almost 7 percent a year since 1980 and is predicted to increase by 5 percent a year for the first twenty years of the twenty-first century.

Resurgence and increased risk of the disease appears to be linked to several factors. Changes in land use, such as mining, logging, and agricultural projects, particularly in the Amazon and Southeast Asia frontier area, are providing new mosquito breeding sites. Other reasons for the disease's spread include global climatic changes, disintegration of health services, armed conflicts, and mass movements of refugees into areas of high malaria transmission.

Reemergence of malaria through mobility occurred in Brazil, for example. Malaria had been practically eradicated from most areas of the Amazon region until massive population movements began to colonize new territories. New highways were built, linking the Amazon to the rest of the country and attracting laborers to work on road construction. In 1970, prior to new road construction in these new areas, there were approximately 50,000 cases of malaria reported; by 1990, reports had increased to more than 500,000, representing 10 percent of the world's reported cases outside Africa.

As a result of the explosion of international travel, imported cases of malaria are now showing up more in developed countries such as the United States Malaria is also reemerging in areas where it was previously under control or eradicated, such as in Korea. According to the WHO, global warming and other climatic events such as El Niño also play a role in increasing the disease. Malaria has now spread to highland areas of Africa, where El Niño effects such as increased rainfall have influenced mosquito breeding sites and hence the transmission of the disease. The emergence of multidrug-resistant strains of parasites is also exacerbating the situation.

Disease Prevention

Prevention of malaria encompasses a variety of measures. Some may protect against infectionthese are directed against mosquitoeswhereas others focus on stopping the development of the disease in human beings. Although only a limited number of drugs are available, if these are used properly and targeted to those at greatest risk, malaria can be reduced.

Since the early 1990s, considerable progress has been made in the search for a malaria vaccine. More than a dozen candidate vaccines are currently in development; some of them are in clinical trials. An effective vaccine could be available within the first twenty years of the twenty-first century. In the meantime, there are a number of prescription drugs available on the market in developed countries that can help prevent malaria, especially in individuals traveling to high incidence areas. Some of the best-known preventatives include Mefloquine, Malarone, and Primaquine.

Medical researchers continue to discover new drug therapies. Most recently, Chinese scientists discovered a drug called artemether that is derived from the Chinese herb qinghaosu. The new drug appears to be as effective as quinine although much slower acting. It may even kill resistant strains of malaria.

see also Interspecies Interactions; Parasitism.

Stephanie A. Lanoue

Bibliography

Noble, Elmer R., Glenn A. Noble, Gerhard A. Schad, and Austin J. MacInnes. Parasitology. London: Lea & Febiger, 1989.

Turkington, Carol, and Bonnie Ashby. Encyclopedia of Infectious Disease. New York: Facts on File, Inc., 1998.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

Lanoue, Stephanie A.. "Malaria." Animal Sciences. 2002. Encyclopedia.com. 27 Jun. 2016 <http://www.encyclopedia.com>.

Lanoue, Stephanie A.. "Malaria." Animal Sciences. 2002. Encyclopedia.com. (June 27, 2016). http://www.encyclopedia.com/doc/1G2-3400500219.html

Lanoue, Stephanie A.. "Malaria." Animal Sciences. 2002. Retrieved June 27, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3400500219.html

Malaria

MALARIA

MALARIA is a disease characterized by chills and fever that recur at regular intervals, anemia, and an enlarged spleen. It is caused by four species of Plasmodium, a protozoan. Long prevalent in Europe and Africa, malaria was probably brought to the Americas by colonists and slaves. By 1700 it had become established from South Carolina to New England. Malaria spread into the Mississippi Valley with the American settlers, where it became a commonly accepted part of life. Generally chronic and debilitating to all ages and often fatal, it placed a heavy burden of ill health on settlers, especially along the waterways that formed the chief routes of commerce.

Malaria reached its height in New England in the eighteenth century and after 1800 appeared only sporadically. In the Midwest it reached its peak about 1875, declining


thereafter quite rapidly in the north. Associated with marshes, malaria in the United States tended to rise with the initial clearing of land and to fall with cultivation and drainage, as Benjamin Rush noted in 1785. Better housing and the development of railroads moved settlement out of the river bottoms, contributing to the decline of malaria.

Cinchona bark, used to treat malaria, was brought to Europe in the 1630s from Peru, and by the eighteenth century was widely used, although often incorrectly. Well into the nineteenth century, American doctors also relied on bloodletting and cathartics. The isolation of quinine by French chemists in 1820 made treatment more practicable, and from the 1850s, quinine was also used to prevent malaria from developing. In 1880 a French army surgeon, Alphonse Laveran, demonstrated the parasitic cause of the disease in the blood of humans. Dr. A. F. A. King of Washington, D.C., correctly speculated on its transmission by mosquito in 1882, and William George MacCollum added significantly to knowledge of the complex life history of the plasmodium in 1897. British physician Ronald Ross made the crucial demonstration of mosquito transmission in 1898. Using anti-mosquito measures and prophylactic quinine, William C. Gorgas in 1901 initiated a campaign that reduced the malaria rate in Havana from 909 per 1,000 in 1899 to 19 per 1,000 in 1908. Later he obtained comparable results in the Canal Zone, which made possible the building of the Panama Canal.

A decline in antimalaria programs in the 1920s, followed by the depression, led in the early 1930s to a resurgence of the disease in the United States, which was curbed under New Deal relief programs. During World War II, both the Public Health Service and the army increased antimalaria programs in the United States, while overseas actions brought home the global importance of the disease. After the war, the Public Health Service, using the newly developed insecticide DDT, inaugurated a program to eradicate malaria in the United States. In 1935, there were about 4,000 malaria deaths in the country, in 1945 about 400, and by 1952 only 25. Since World War II the United States has also participated in anti-malaria campaigns in other countries. Although these efforts have greatly reduced the incidence of malaria, it remains a major health problem in many of the less developed countries.

BIBLIOGRAPHY

Ackerknecht, Erwin Heinz. Malaria in the Upper Mississippi Valley, 1760–1900. Baltimore: John Hopkins Press, 1945; New York: Arno Press, 1977.

Jaramillo-Arango, Jaime. The Conquest of Malaria. London: W. Heinemann, 1950.

Russell, Paul Farr. Man's Mastery of Malaria. London, New York: Oxford University Press, 1955.

Shuler, Alexandria V. Malaria: Meeting the Global Challenge. Boston: Oelgeschlager, Gunn, and Hain, 1986.

John B.Blake/h. s.

See alsoEpidemics and Public Health ; "Silent Spring."

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Malaria." Dictionary of American History. 2003. Encyclopedia.com. 27 Jun. 2016 <http://www.encyclopedia.com>.

"Malaria." Dictionary of American History. 2003. Encyclopedia.com. (June 27, 2016). http://www.encyclopedia.com/doc/1G2-3401802505.html

"Malaria." Dictionary of American History. 2003. Retrieved June 27, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3401802505.html

malaria

malaria, infectious parasitic disease that can be either acute or chronic and is frequently recurrent. Malaria is common in Africa, Central and South America, the Mediterranean countries, Asia, and many of the Pacific islands. In the United States it was found in the South and less frequently in the northern and western parts of the country.

Plasmodium falciparum is the most deadly of all the five Plasmodium parasites that typically cause malaria in humans. All the species require both the Anopheles mosquito and humans to complete the life cycle. Sexual reproduction of the protozoans occurs in the mosquito; an immature form is then transmitted to the human via the bite of the mosquito. In a person the parasite goes to the liver, replicates, and moves into the bloodstream, where it attacks red blood cells for their hemoglobin. Some of the plasmodia become sexually mature and are transmitted back to another biting mosquito. P. knowlesi, however, is primarily transmitted from monkeys to humans via mosquitoes.

Symptoms

At the onset of malaria, bouts of chills (ague) and fever lasting several hours and occurring every three or four days are the usual symptoms. If the disease is not treated, the spleen and the liver become enlarged, anemia develops, and jaundice appears. Death may occur from general debility, anemia, or clogging of the vessels of cerebral tissues by affected red blood cells. Cerebral malaria is most commonly seen in infants, pregnant women, and nonimmune travelers to endemic areas.

Immune Response

P. falciparum creates protein knobs on the surfaces of the red blood cells it attacks. These knobs attach the cell to the lining of the blood vessel, preventing its removal to the spleen for destruction. The parasite slows detection by the immune system by changing the makeup of the knobs periodically, substituting or rearranging its 150 "var" (variability) genes, a strategy unique to malaria. A pattern of remission and relapse results as the immune system learns each new "code" only to have it again changed. Patients with malaria gradually do develop immunity that modifies the course of the disease, but this immunity has a degree of strain specificity. Some of the Plasmodium species have the ability to persist in the liver and cause a new infection years after the original one.

Treatment and Control

The bark of the cinchona and its product, quinine, have been used in the treatment of malaria for centuries. After World War II, they were largely replaced by the synthetic analog chloroquine. The use of chloroquine, in addition to the use of DDT for mosquito control, was expected to eradicate the disease, but a World Health Organization campaign (1955–69) to eradicate the disease globally (by controlling mosquitoes long enough to allow the human population to become disease free) proved unsuccessful. Despite that, spraying successfully eradicated the disease in some areas (Sardinia, Japan, and Taiwan). In the United States, the disease, which had been endemic in many SE states, was eradicated in 1951.

In the 1960s several strains of the malarial parasite developed resistance to chloroquine. This, plus the growing immunity of mosquitoes to insecticides, caused malaria to become one the of world's leading re-emerging infectious diseases, infecting some 225 million people a year and killing more than 650,000 in 2010. Those numbers may be significant underestimates. By 2010, however, the number of infections was again falling due to improved malaria control in Africa.

Mefloquine may be used in areas where the disease has become highly resistant to chloroquine, but some strains are now resistant to it and other drugs. Artemisinin (derived from sweet wormwood) in combination with other drugs is now in many cases the first-line treatment in many cases, but resistance to it also has developed, in parts of SE Asia. Amodiaquine in combination with sulfadoxine and pyrimethamine has also been shown to be effective, and malarone (atovaquone and proguanil) also is used for resistant strains. The use of combinations of drugs with different modes of actions increases the effectiveness of treatment and helps reduce the development of drug resistance.

Vaccines against malaria remain experimental. Spraying is still used to control malaria-transmitting mosquitoes, and more recently the use of mosquito nets treated with a long-lasting insecticide has become widespread. Fish that feed on mosquito larvae also have been employed to control mosquitoes.

See studies by M. Humphreys (2001), S. Shah (2010), B. Shore (2010), and R. M. Packard (2011).

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"malaria." The Columbia Encyclopedia, 6th ed.. 2016. Encyclopedia.com. 27 Jun. 2016 <http://www.encyclopedia.com>.

"malaria." The Columbia Encyclopedia, 6th ed.. 2016. Encyclopedia.com. (June 27, 2016). http://www.encyclopedia.com/doc/1E1-malaria.html

"malaria." The Columbia Encyclopedia, 6th ed.. 2016. Retrieved June 27, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1E1-malaria.html

malaria

malaria (ague, marsh fever, periodic fever, paludism) (mă-lair-iă) n. an infectious disease due to the presence of parasitic protozoa of the genus Plasmodium within the red blood cells. The disease is transmitted by the Anopheles mosquito and is confined mainly to tropical and subtropical areas. After an incubation period varying from 12 days to 10 months parasites invade, multiply within, and eventually destroy the red blood cells, releasing new parasites. This causes a short bout of shivering, fever, and sweating, and the loss of healthy red cells results in anaemia. When the next batch of parasites is released symptoms reappear. The interval between fever attacks varies in different types of malaria. Preventive and curative treatment relies on such drugs as chloroquine and proguanil. benign m. malaria caused by P. vivax, P. malariae, or P. ovale, with intervals of 2–3 days between fever attacks. falciparum (or malignant) m. the most severe form of malaria, in which the interval between fever attacks varies from a few hours to 2 days.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"malaria." A Dictionary of Nursing. 2008. Encyclopedia.com. 27 Jun. 2016 <http://www.encyclopedia.com>.

"malaria." A Dictionary of Nursing. 2008. Encyclopedia.com. (June 27, 2016). http://www.encyclopedia.com/doc/1O62-malaria.html

"malaria." A Dictionary of Nursing. 2008. Retrieved June 27, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O62-malaria.html

Malaria

MALARIA

DEFINITION


Malaria is a serious, infectious disease spread by certain kinds of mosquitoes. It is common in tropical climates and is characterized by chills, fevers, and an enlarged spleen. These symptoms reappear again and again. The disease can be treated with medication, but it tends to come back even after being cured. Malaria is endemic in many developing countries. An endemic disease is one that occurs frequently in a particular location. Isolated, limited outbreaks of malaria sometimes occur in the United States.

DESCRIPTION


Malaria is not a serious problem in the United States. Over the past ten years, only about 1,200 cases have been reported each year in this country. In most cases, a person was infected outside the United States while traveling on business or on vacation.

Malaria is a far more serious problem in other parts of the world. Between 300 million and 500 million people in Africa, India, Southeast Asia, the Middle East, the South Pacific, and Central and South America have the disease. About two million people die of the disease every year. Most of these deaths occur in southern Africa.

A person can have malaria more than once. In some parts of Africa, people have up to forty bouts of malaria during their lifetime. Malaria is becoming a more serious problem because the organisms that cause the disease are growing resistant to the drugs used to treat it.

CAUSES


Malaria is caused by four different kinds of parasites belonging to the plasmodium family. A parasite is an organism that lives off another organism. Animals can also get malaria, but malaria cannot be passed from humans to animals or from animals to humans.

Malaria is transmitted by female mosquitoes that carry the parasite in their bodies. When the mosquito bites a human, it injects a small amount of its saliva into the human's bloodstream. The saliva contains parasites that travel through the person's bloodstream to his or her liver. There, the parasites reproduce. Eventually, they leave the liver and travel back into the bloodstream. Once in the bloodstream, they begin to cause the symptoms of malaria.

Malaria cannot be passed directly from one human to another. It can be transmitted by a mosquito. A mosquito may bite a person infected with the malaria parasite. When it sucks the person's blood, it takes in some of the parasites. If the same mosquito bites a second person, it may transfer those parasites to the uninfected person.

Malaria can also be transmitted through blood transfusions. If an infected person donates blood, the blood will contain malaria parasites. If the blood is put into another person's body, the parasites will also flow into his or her bloodstream. For this reason, blood donors are often screened for the malaria parasite before they are allowed to give blood.

The incubation period for malaria varies considerably. An incubation period is the time between the mosquito bite and the time symptoms of malaria begin to appear. The incubation period differs depending on the kind of parasite involved. For the most serious form of malaria, the incubation period is eight to twelve days. In some rare forms of malaria, the incubation period can be as long as ten months.

Malaria: Words to Know

Artemisinin:
An antimalarial herb used for many years in China under the name qiinghaosu.
Chloroquine:
An antimalarial drug first used in the 1940s as a substitute for quinine, and still widely used in Africa because of its relatively low cost.
Mefloquine:
An antimalarial drug developed by the U.S. Army in the early 1980s.
Quinine:
One of the first successful treatments for malaria, derived from the bark of the cinchona tree.
Sulfadoxine/pyrimethamine (trade name Fansidar):
An antimalarial drug developed in the 1960s, often used in areas where quinine and chloroquine are no longer effective.

SYMPTOMS


A person infected with malaria passes through three stages of very distinctive symptoms. The first stage is characterized by uncontrollable shivering for an hour or two. In the next stage, the patient's temperature rises quickly. It may reach 106°F (41°C) for a period of up to six hours. In the third stage, the patient begins to sweat profusely, and his or her temperature drops rapidly.

Other symptoms may accompany these stages. They include fatigue, severe headache, nausea, and vomiting. After the third stage, the patient often falls asleep from exhaustion.

The three stages are often repeated the following day, two days later, or at some later time. In many cases, a person experiences a repetition of the stages again and again during their lifetime. Some people go many years before the symptoms repeat.

The most serious forms of malaria can result in death in a matter of hours. The parasites attack a person's red blood cells and change their structure. The cells become very sticky and begin to clump together. As they do, they may block blood vessels in vital organs, such as the kidneys and spleen. These organs may no longer be able to function properly, and the patient may fall into a coma and die.

DIAGNOSIS


Malaria can be diagnosed with a blood test. A sample of a patient's blood is taken and studied under a microscope to detect the presence of parasites. Blood tests sometimes need to be repeated after a seventy-two-hour period to confirm the diagnosis.

The three stages of malaria can also be used to diagnose the disease. A person who lives in an area where malaria is common and who has chills, fever, and a very high temperature should have a blood test as quickly as possible.

Malaria is sometimes misdiagnosed in North America. The disease is not very common in this part of the world, and its symptoms are similar to those of the flu (see influenza entry). A doctor may think that a person has the flu when he or she really has malaria. This kind of misdiagnosis can result in the patient's death if he or she has a severe case of malaria.

AN ANCIENT ILLNESS

Malaria has been a known disease for centuries and was described in medical records from ancient China, India, and Greece. Doctors first believed that malaria was caused by poisonous vapors in the air. People who lived around swamps, bogs, and other wetlands were especially likely to get the disease. Therefore, it was presumed that it must be the "bad gases" given off by these watery regions. In fact, the name of the disease comes from two Italian words for "bad air": mal- ("bad") and -aria ("air").

The Romans are credited with one of the most successful attempts to eliminate malaria. They drained large areas of swampy land around the city, believing that they were cutting off the supply of "bad gases." In fact, they were destroying the wet areas in which malaria carriers (the mosquitoes) lived and bred.

TREATMENT


Malaria can be treated with drugs. However, treatment is complicated by a number of factors. First, each type of malaria requires a different drug. Second, the treatment depends on the region of the world in which the person was infected. The kinds of parasites living in different parts of the world respond in different ways to different drugs.

The classic treatment for malaria is quinine. Quinine is still effective in treating some forms of malaria in some parts of the world, but other parasites have developed a resistance to quinine.

If quinine is not effective, a variety of antibiotics can be tried. These include tetracycline (pronounced tet -ruh-SIE-kleen), clindamycin (pronounced klin-duh-MY-suhn, trade name Cleocin), mefloquine (pronounced MEF-luhkwine, trade name Lariam), or sulfadoxine/pyrimethamine (pronounced sullfuh-DOK-seen/pi-ruh-METH-uh-meen, trade name Fansidar). A modified form of quinine known as chloroquine (pronounced KLOR-uh-kween) can also be used. In some parts of the world, the parasite that causes the most serious form of malaria is resistant to all known drugs.

Patients with very serious cases of malaria may require hospitalization and special treatments. These treatments may include intravenous fluids (fluids injected into the patient's bloodstream), blood transfusions, kidney dialysis, and oxygen therapy to help him or her breathe.

Alternative Treatment

The Chinese herb qinghao (known as artemesia in the West) has long been used to treat malaria. However, it is not approved for use in the United States and other parts of the developed world. Researchers are still concerned about the herb's possibly dangerous side effects.

Some practitioners suggest using certain herbs to protect against malaria and to strengthen the liver. These herbs include wormwood, goldenseal, Chinese goldenthread, and milk thistle.

PROGNOSIS


If treated in its early stages, malaria can be cured. Cures are more difficult for people who live in areas where malaria is endemic. These people may be bitten by mosquitoes and exposed to malaria parasites again and again and may never fully recover from the disease.

PREVENTION


Malaria can be prevented in one of two ways. First, a person can avoid being bitten by a mosquito carrying the malaria parasite. The World Health Organization (WHO) has been working to eliminate malaria for more than thirty years. Its approach has been to kill as many of the mosquitoes that cause malaria as possible. For some years, WHO was quite successful in this effort. It used DDT and other pesticides to kill mosquitoes. Unfortunately, mosquitoes have slowly become resistant to many pesticides. It has become more and more difficult to kill mosquitoes with the pesticides now available.

The second method for avoiding malaria is to take drugs that protect against the disease. These drugs kill parasites as soon as they enter the bloodstream. The problem is that antimalarial drugs are expensive. Most people in Africa, Asia, and other areas where malaria is common cannot afford them.

Scientists have long hoped to find a vaccine for malaria. With a vaccine, a person could be protected for a lifetime with one or a few shots. So far, however, researchers have had no success in producing such a vaccine.

People who travel in areas where malaria is common can protect themselves by wearing mosquito repellent. The compound known as DEET is one of the most effective repellents, but it can have harmful side effects, especially in children. It should be used only with caution.

Certain other preventive measures can also be followed, including:

  • Staying indoors in well-screened areas between dusk and dawn
  • Sleeping inside mosquito nets that have been soaked with mosquito repellent
  • Wearing clothes that cover the entire body

People who plan trips to areas in which malaria is endemic should take antimalarial drugs as a preventive against contracting the disease. The drugs usually prescribed are chloroquine or mefloquine. A person starts taking the drugs a few days before leaving on the trip. He or she continues to take the drugs while on the trip and for at least four weeks after they return home.

FOR MORE INFORMATION


Books

Desowitz, Robert S. The Malaria Capers: More Tales of Parasites and People, Research, and Reality. New York: W. W. Norton, 1993.

Stoffman, Phyllis. The Family Guide to Preventing and Treating 100 Infectious Illnesses. New York: John Wiley & Sons, 1995.

Periodicals

Kristof, Nicholas D. "Malaria Makes a Comeback, Deadlier Than Ever." New York Times (January 8, 1997).

Mack, Alison. "Collaborative Efforts Under Way to Combat Malaria." Scientist (May 12, 1997): p. 1+.

Shell, Ellen Ruppel. "Resurgence of a Deadly Disease." Atlantic Monthly (August 1997).

Organizations

Centers for Disease Control Malaria Hotline. (770) 332-4555.

Centers for Disease Control Travelers Hotline. (770) 332-4559.

Malaria Foundation International. http://www.malaria.org.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Malaria." UXL Complete Health Resource. 2001. Encyclopedia.com. 27 Jun. 2016 <http://www.encyclopedia.com>.

"Malaria." UXL Complete Health Resource. 2001. Encyclopedia.com. (June 27, 2016). http://www.encyclopedia.com/doc/1G2-3437000191.html

"Malaria." UXL Complete Health Resource. 2001. Retrieved June 27, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3437000191.html

Malaria

Malaria

What Is Malaria?

How Common Is Malaria?

Is Malaria Contagious?

What Are the Signs and Symptoms of Malaria?

How Is Malaria Diagnosed and Treated?

Can Malaria Be Prevented?

Resources

Malaria (mah-LAIR-e-uh) is a disease caused by a parasite that is spread to humans by the bite of an infected mosquito.

KEYWORDS

for searching the Internet and other reference sources

Anopheles mosquito

Chloroquine Mosquito-borne illness

Plasmodium

Quinine

What Is Malaria?

Malaria, which literally means bad air, was once thought to be spread in the air around stagnant marshes. It is now known that mosquitoes, particularly female Anopheles (a-NOH-fel-eez) mosquitoes, spread the parasites that cause malaria. Four different species of a parasite in the genus Plasmodium (plaz-MO-dee-um) cause malaria. They are falciparum (fal-SIP-ar-um), malariae (ma-LAIR-e-eye), ovale (o-VAL-e), and vivax (VIvax). Of the four, P. falciparum is the most common and the most deadly. Plasmodium requires time in both the mosquito vector* and human host* to complete its life cycle.

*vector
(VEK-tor) is an animal or insect that carries a disease-causing organism and transfers it from one host to another.
*host
is an organism that provides another organism (such as a parasite or virus) with a place to live and grow.

How Common Is Malaria?

Forty percent of the worlds population is at risk for contracting malaria from infected mosquitoes, primarily in tropical and subtropical regions. Worldwide, there are 300 to 500 million cases of malaria and more than one million deaths from malaria each year. More than 90 percent of all malaria deaths occur in sub-Saharan Africa, a vast area south of the Sahara Desert, and 75 percent of deaths occur in children. Plasmodium falciparum causes malaria in this region, and poverty, poor nutrition, and poor access to health care all contribute to the high death rate. Malaria is increasingly common in Central and South America, Asia, the Middle East, and the Pacific Islands. About 1,200 cases of malaria are diagnosed in the United States each year, mostly in recent immigrants or travelers from countries where malaria is found.

Mosquito control has virtually eliminated malaria in areas with temperate climates. However, the disease is making a comeback as mosquitoes become resistant to insecticides and Plasmodium becomes resistant to medications used to treat malaria.

Is Malaria Contagious?

Malaria is not passed directly from one person to another. Mosquitoes spread the disease. When a mosquito bites an infected person, it ingests malaria parasites contained in that persons blood. The parasites need an incubation period* of about 1 week in the mosquito before the mosquito can spread the disease when it bites another person. Once in a persons body, the parasites travel to the liver where they can remain dormant, or inactive, for months or even years. In the liver, the parasites grow and multiply and are then ready to move into the bodys red blood cells, where they continue to grow until the red blood cells burst, freeing more parasites to attack more blood cells. The parasite can be ingested by a mosquito and spread to another person only during the time that Plasmodium is in the blood.

*incubation
(ing-kyoo-BAY-shun) period is the time between infection by a germ and when symptoms first appear. Depending on the germ, this period can be from hours to months.

In most of Latin America, Africa, the Middle East, and Asia, people are at a higher risk of getting malaria. Drug-resistant malaria has caused the disease to be on the rise in these parts of the world.

What Are the Signs and Symptoms of Malaria?

Malaria causes fever and symptoms similar to those of the flu. In the early stages of the disease when the parasite is in the liver, the infected person does not feel sick. When the parasites invade the red blood cells and cause them to burst, toxins (poisons that harm the body) are released into the blood and the person experiences fever, chills, sweating, headache, muscle aches, and tiredness. Symptoms typically begin 9 to 16 days after infection with the parasite, but the time may vary depending on the infecting species. Episodes of these symptoms reoccur every 48 to 72 hours. Other symptoms may include nausea (NAW-zee-uh), vomiting, and diarrhea (dye-uh-REE-uh).

How Is Malaria Diagnosed and Treated?

Under the microscope, a blood sample from a person who has malaria will show one of the four species of Plasmodium parasites within the red blood cells. Malaria is treated with antimalarial drugs, many of them derived from quinine, which is found naturally in the bark of the cinchona tree from Peru. Which drug is chosen to treat a patient depends on the parasite causing the infection, the severity of symptoms, the age of the patient, and whether the parasite is resistant to certain drugs. Some patients may need intensive hospital care.

Treatment can last several weeks or months. In some infections, the parasite can remain dormant in the liver for months or years and the disease may return even after treatment. Destruction of red blood cells in cases of malaria can result in anemia* and jaundice*. Severe and untreated infection may cause liver and kidney* problems, seizures*, mental confusion, coma*, and death; malaria is fatal in 1 in 500 cases. Children and pregnant women are particularly vulnerable to complications. Infected pregnant women are at risk for miscarriage*, premature delivery*, and stillbirth*, and anemia in children can have long-term effects on growth and development.

*anemia
(uh-NEE-me-uh) is a blood condition in which there is a decreased amount of oxygen-carrying hemoglobin in the blood and, usually, fewer than normal numbers of red blood cells.
*jaundice
(JON-dis) is a yellowing of the skin, and sometimes the whites of the eyes, caused by a buildup in the body of bilirubin, a chemical produced in and released by the liver. An increase in bilirubin may indicate disease of the liver or certain blood disorders.
*kidney
is one of the pair of organs that filter blood and remove waste products and excess water from the body in the form of urine.
*seizures
(SEE-zhurs) are sudden bursts of disorganized electrical activity that interrupt the normal functioning of the brain, often leading to uncontrolled movements in the body and sometimes a temporary change in consciousness.
*coma
(KO-ma) is an unconscious state in which a person cannot be awakened and cannot move, see, speak, or hear.
*miscarriage
is the ending of a pregnancy through the death of the embryo or fetus before birth.
*premature delivery
is when a baby is born before it has reached full term.
*stillbirth
is the birth of a dead fetus.

Can Malaria Be Prevented?

In areas where malaria is endemic*, people can avoid being bitten by mosquitoes by wearing long-sleeved shirts and long pants, using insect

*endemic
(en-DEH-mik) describes a disease or condition that is present in a population or geographic area at all times.

Scientists, in searching for alternative means of malaria control, have recently been able to genetically modify mosquitoes carrying a form of malaria that affects rodents. The genetically modified mosquitoes were less susceptible to infection after feeding on a malaria-infected mouse and were far less likely than normal mosquitoes to transmit the malaria parasite to other mice. Phototake

repellent, and staying in a screened or air-conditioned room from dusk to dawn when mosquitoes are most active. Bed nets treated with certain insecticides repel mosquitoes for 6 to 12 months. Travelers to foreign countries where malaria is found should take preventive drugs prescribed by a doctor before leaving.

Scientists are working to develop a vaccine that will prevent malaria. However, the different species of Plasmodium and the complicated life cycle of these parasites have made developing a vaccine difficult.

See also

West Nile Fever

Yellow Fever

Resources

Book

Jones, Ann. Looking for Lovedu: Days and Nights in Africa. Knopf: New York, 2001. The authors account of her journey across Africa in search of the legendary Lovedu tribe is full of adventure and complications such as malaria.

Organization

World Health Organization (WHO), Avenue Appia 20, 1211 Geneva 27, Switzerland. WHO provides information about malaria at its website.

Telephone 011-41-22-791-2111 http://www.who.int

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"Malaria." Complete Human Diseases and Conditions. 2008. Encyclopedia.com. 27 Jun. 2016 <http://www.encyclopedia.com>.

"Malaria." Complete Human Diseases and Conditions. 2008. Encyclopedia.com. (June 27, 2016). http://www.encyclopedia.com/doc/1G2-3497700249.html

"Malaria." Complete Human Diseases and Conditions. 2008. Retrieved June 27, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3497700249.html

malaria

malaria Parasitic disease resulting from infection with one of four species of Plasmodium protozoan. Transmitted by the Anopheles mosquito, it is characterized by fever and enlargement of the spleen. Attacks of fever, chills, and sweating typify the disease, and recur as new generations of parasites develop in the blood. The original antimalarial drug, quinine, gave way to synthetics such as chloroquine. With 270 million people infected, malaria is one of the most widespread diseases, claiming two million lives a year.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"malaria." World Encyclopedia. 2005. Encyclopedia.com. 27 Jun. 2016 <http://www.encyclopedia.com>.

"malaria." World Encyclopedia. 2005. Encyclopedia.com. (June 27, 2016). http://www.encyclopedia.com/doc/1O142-malaria.html

"malaria." World Encyclopedia. 2005. Retrieved June 27, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O142-malaria.html

malaria

ma·lar·i·a / məˈlerēə/ • n. an intermittent and remittent fever caused by a protozoan parasite that invades the red blood cells. The parasite belongs to the genus Plasmodium (phylum Sporozoa) and is transmitted by female mosquitoes of the genus Anopheles. DERIVATIVES: ma·lar·i·al / -ēəl/ adj. ma·lar·i·an / -ēən/ adj. ma·lar·i·ous / -ēəs/ adj.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"malaria." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. 27 Jun. 2016 <http://www.encyclopedia.com>.

"malaria." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. (June 27, 2016). http://www.encyclopedia.com/doc/1O999-malaria.html

"malaria." The Oxford Pocket Dictionary of Current English. 2009. Retrieved June 27, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O999-malaria.html

malaria

malaria A disease caused by the parasitic protozoan Plasmodium, which requires two hosts, the bloodsucking female Anopheles mosquito and a human, in order to complete its complex life cycle. Symptoms of fever and anaemia in humans are caused by invasion and destruction of the red blood cells during an asexual phase of the life cycle. See Apicomplexa.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"malaria." A Dictionary of Biology. 2004. Encyclopedia.com. 27 Jun. 2016 <http://www.encyclopedia.com>.

"malaria." A Dictionary of Biology. 2004. Encyclopedia.com. (June 27, 2016). http://www.encyclopedia.com/doc/1O6-malaria.html

"malaria." A Dictionary of Biology. 2004. Retrieved June 27, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O6-malaria.html

malaria

malaria fever formerly supposed to be caused by exhalations from marshy places. XVIII. — It. mal'aria for mala aria ‘bad AIR’; cf. MAL-.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

T. F. HOAD. "malaria." The Concise Oxford Dictionary of English Etymology. 1996. Encyclopedia.com. 27 Jun. 2016 <http://www.encyclopedia.com>.

T. F. HOAD. "malaria." The Concise Oxford Dictionary of English Etymology. 1996. Encyclopedia.com. (June 27, 2016). http://www.encyclopedia.com/doc/1O27-malaria.html

T. F. HOAD. "malaria." The Concise Oxford Dictionary of English Etymology. 1996. Retrieved June 27, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O27-malaria.html

malaria

malariabarrier, carrier, farrier, harrier, tarrier •Calabria, Cantabria •Andrea • Kshatriya • Bactria •Amu Darya, aria, Zaria •Alexandria •Ferrier, terrier •destrier •aquaria, area, armamentaria, Bavaria, Bulgaria, caldaria, cineraria, columbaria, filaria, frigidaria, Gran Canaria, herbaria, honoraria, malaria, pulmonaria, rosaria, sacraria, Samaria, solaria, tepidaria, terraria •atria, gematria •Assyria, Illyria, Styria, SyriaLaurier, warrior •hypochondria, mitochondria •Austria •auditoria, ciboria, conservatoria, crematoria, emporia, euphoria, Gloria, moratoria, phantasmagoria, Pretoria, sanatoria, scriptoria, sudatoria, victoria, Vitoria, vomitoria •Maurya •courier, Fourier •currier, furrier, spurrier, worrier •Cumbria, Northumbria, Umbria •Algeria, anterior, bacteria, Bashkiria, cafeteria, criteria, cryptomeria, diphtheria, exterior, hysteria, Iberia, inferior, interior, Liberia, listeria, Nigeria, posterior, Siberia, superior, ulterior, wisteria •Etruria, Liguria, Manchuria, Surya

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"malaria." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. 27 Jun. 2016 <http://www.encyclopedia.com>.

"malaria." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. (June 27, 2016). http://www.encyclopedia.com/doc/1O233-malaria.html

"malaria." Oxford Dictionary of Rhymes. 2007. Retrieved June 27, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O233-malaria.html

Facts and information from other sites