The word elephantiasis is a vivid and accurate term for the syndrome it describes: the gross (visible) enlargement of the arms, legs, or genitals to elephantoid size.
True elephantiasis is the result of a parasitic infection caused by three specific kinds of round worms. The long, threadlike worms block the body's lymphatic system—a network of channels, lymph nodes, and organs that helps maintain proper fluid levels in the body by draining lymph from tissues into the bloodstream. This blockage causes fluids to collect in the tissues, which can lead to great swelling, called "lymphedema." Limbs can swell so enormously that they resemble an elephant's foreleg in size, texture, and color. This is the severely disfiguring and disabling condition of elephantiasis.
There are a few different causes of elephantiasis, but the agents responsible for most of the elephantiasis in the world are filarial worms: white, slender round worms found in most tropical and subtropical places. They are transmitted by particular kinds (species) of mosquitoes, that is, bloodsucking insects. Infection with these worms is called "lymphatic filariasis" and over a long period of time can cause elephantiasis.
Lymphatic filariasis is a disease of underdeveloped regions found in South America, Central Africa, Asia, the Pacific Islands, and the Caribbean. It is a disease that has been present for centuries, as ancient Persian and Indian writings clearly described elephant-like swellings of the arms, legs, and genitals. It is estimated that 120 million people in the world have lymphatic filariasis. The disease appears to be spreading, in spite of decades of research in this area.
Other terms for elephantiasis are Barbados leg, elephant leg, morbus herculeus, mal de Cayenne, and myelolymphangioma.
Other situations that can lead to elephantiasis are:
- a protozoan disease called leishmaniasis
- a repeated streptococcal infection
- the surgical removal of lymph nodes (usually to prevent the spread of cancer )
- a hereditary birth defect
Causes and symptoms
Three kinds of round worms cause elephantiasis filariasis: Wuchereria bancrofti, Brugia malayi, and Brugia timori. Of these three, W. bancrofti makes up about 90% of the cases. Man is the only known host of W. bancrofti.
Culex, Aedes, and Anopheles mosquitoes are the carriers of W. bancrofti. Anopheles and Mansonia mosquitoes are the carriers of B. malayi. In addition, Anopheles mosquitoes are the carriers of B. timori.
Infected female mosquitoes take a blood meal from a human, and in doing so, introduce larval forms of the particular parasite they carry to the person. These larvae migrate toward a lymphatic channel, then travel to various places within the lymphatic system, usually positioning themselves in or near lymph nodes throughout the body. During this time, they mature into more developed larvae and eventually into adult worms. Depending upon the species of round worm, this development can take a few months or more than a year. The adult worms grow to about 1 in (2.5 cm) to 4 in (10 cm) long.
The adult worms can live from about three to eight years. Some have been known to live to 20 years, and in one case 40 years. The adult worms begin reproducing numerous live embryos, called microfilariae. The microfilariae travel to the bloodstream, where they can be ingested by a mosquito when it takes a blood meal from the infected person. If they are not ingested by a mosquito, the microfilariae die within about 12 months. If they are ingested by a mosquito, they continue to mature. They are totally dependent on their specific species of mosquito to develop further. The cycle continues when the mosquito takes another blood meal.
Most of the symptoms an infected person experiences are due to the blockage of the lymphatic system by the adult worms and due to the substances (excretions and secretions) produced by the worms.
The body's allergic reactions may include repeated episodes of fever, shaking chills, sweating, headaches, vomiting, and pain. Enlarged lymph nodes, swelling of the affected area, skin ulcers, bone and joint pain, tiredness, and red streaks along the arm or leg also may occur. Abscesses can form in lymph nodes or in the lymphatic vessels. They may appear at the surface of the skin as well.
Long-term infection with lymphatic filariasis can lead to lymphedema, hydrocele (a buildup of fluid in any saclike cavity or duct) in the scrotum, and elephantiasis of the legs, scrotum, arms, penis, breasts, and vulvae. The most common site of elephantiasis is the leg. It typically begins in the ankle and progresses to the foot and leg. At first the swollen leg may feel soft to the touch but eventually becomes hard and thick. The skin may appear darkened or warty and may even crack, allowing bacteria to infect the leg and complicate the disease. The microfilariae usually don't cause injury. In some instances, they cause "eosinophilia," an increased number of eosinophils (a type of white blood cells) in the blood.
This disease is more intense in people who never have been exposed to lymphatic filariasis than it is in the native people of tropical areas where the disease occurs. This is because many of the native people often are immunologically tolerant.
The only sure way to diagnose lymphatic filariasis is by detecting the parasite itself, either the adult worms or the microfilariae.
Microscopic examination of the person's blood may reveal microfilariae. But many times, people who have been infected for a long time do not have microfilariae in their bloodstream. The absence of them, therefore, does not mean necessarily that the person is not infected. In these cases, examining the urine or hydrocele fluid or performing other clinical tests is necessary.
Collecting blood from the individual for microscopic examination should be done during the night when the microfilariae are more numerous in the bloodstream. (Interestingly, this is when mosquitoes bite most frequently.) During the day microfilariae migrate to deeper blood vessels in the body, especially in the lung. If it is decided to perform the blood test during the day, the infected individual may be given a "provocative" dose of medication to provoke the microfilariae to enter the bloodstream. Blood then can be collected an hour later for examination.
Detecting the adult worms can be difficult because they are deep within the lymphatic system and difficult to get to. Biopsies usually are not performed because they usually don't reveal much information.
The drug of choice in treating lymphatic filariasis is diethylcarbamazine (DEC). The trade name in the United States is Hetrazan.
The treatment schedule is typically 2 mg/kg per day, three times a day, for three weeks. The drug is taken in tablet form.
DEC kills the microfilariae quickly and injures or kills the adult worms slowly, if at all. If all the adult worms are not killed, remaining paired males and females may continue to produce more larvae. Therefore, several courses of DEC treatment over a long time period may be necessary to rid the individual of the parasites.
DEC has been shown to reduce the size of enlarged lymph nodes and, when taken long-term, to reduce elephantiasis. In India, DEC has been given in the form of a medicated salt, which helps prevent spread of the disease.
The side effects of DEC almost all are due to the body's natural allergic reactions to the dying parasites rather than to the DEC itself. For this reason, DEC must be given carefully to reduce the danger to the individual. Side effects may include fever, chills, headache, dizziness, nausea and vomiting, itching, and joint pain. These side effects usually occur within the first few days of treatment. These side effects usually subside as the individual continues taking the drug.
There is an alternate treatment plan for the use of DEC. This plan is designed to kill the parasites slowly (to reduce allergic reactions to the dead microfilariae and dying adult worms within the body). Lower doses of DEC are taken for the first few days, followed by the higher dose of 2 mg/kg per day for the remaining three weeks. In addition, steroids may be prescribed to prevent the individual's body from reacting severely to the dead worms.
Another drug used is Ivermectin. Early research studies of Ivermectin show that it is excellent in killing microfilariae, but the effects of this drug on the adult worms are still being investigated. It is probable that patients will need to continue using DEC to kill the adult worms. Mild side effects of Ivermectin include headache, fever, and myalgia.
Other means of managing lymphatic filariasis are pressure bandages to wrap the swollen limb and elastic stockings to help reduce the pressure. Exercising and elevating a bandaged limb also can help reduce its size.
Surgery can be performed to reduce elephantiasis by removing excess fatty and fibrous tissue, draining the swelled area, and removing the dead worms.
With DEC treatment, the prognosis is good for early and mild cases of lymphatic filariasis. The prognosis is poor, however, for heavy parasitic infestations.
The two main ways to control this disease are to take DEC preventively, which has shown to be effective, and to reduce the number of carrier insects in a particular area.
Avoiding mosquito bites with insecticides and insect repellents is helpful, as is wearing protective clothing and using bed netting.
Much effort has been made in cleaning the breeding sites (stagnant water) of mosquitoes near people's homes in areas where filariasis is found.
Before visiting countries where lymphatic filariasis is found, it would be wise to consult a travel physician to learn about current preventative measures.
National Lymphedema Network. 2211 Post St., Suite 404, San Francisco, CA 94115. (800) 541-3259. 〈http:// www.hooked.net〉.
National Organization for Rare Disorders. PO Box 8923, New Fairfield, CT 06812-8923. (800) 999-6673. 〈http://www.rarediseases.org〉.
Antigen— Any substance (usually a protein) that causes an immune response by the body to produce antibodies.
Filarial— Threadlike. The word "filament" is formed from the same root word.
Host— A person or animal in which a parasite lives, is nourished, grows, and reproduces.
Lymph— A watery substance that collects in the tissues and organs of the body and eventually drains into the bloodstream.
Lymphatic system— A network composed of vessels, lymph nodes, the tonsils, the thymus gland, and the spleen. It is responsible for transporting fluid and nutrients to the bloodstream and for maturing certain blood cells that are part of the body's immune system.
Lymphedema— The unnatural accumulation of lymph in the tissues of the body, which results in swelling in that area.
Protozoa— (Plural form of protozoan) Single-celled organisms (not bacteria) of which about 30 kinds cause disease in humans.
Streptococcal— Pertaining to any of the Streptococcus bacteria. These organisms can cause pneumonia, skin infections, and many other diseases.
"Elephantiasis." Gale Encyclopedia of Medicine, 3rd ed.. . Encyclopedia.com. (May 28, 2017). http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/elephantiasis-0
"Elephantiasis." Gale Encyclopedia of Medicine, 3rd ed.. . Retrieved May 28, 2017 from Encyclopedia.com: http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/elephantiasis-0
elephantiasis (ĕl´əfăntī´əsĬs), abnormal enlargement of any part of the body due to obstruction of the lymphatic channels in the area (see lymphatic system), usually affecting the arms, legs, or external genitals. In tropical countries the most common cause is filariasis, infestation with certain filaria, small parasitic roundworms (see worm) of the genera Wuchereria bancrofti or Brugia malayi that are introduced into the body by many species of mosquitoes. The adult worms live in the lymphatic system, causing local inflammation, fibrosis, and obstruction, and resulting in the characteristic enlargement and thickening of the skin. The initial damage done by the worms can be greatly worsened by secondary bacterial and fungal infections.
Recovery from filariasis is possible and surgery sometimes helps, but any elephantiasis that develops during the disease cannot be cured. Ivermectin, an antifilarial drug, has been effective with a single dose. Diethylcarbamazine often kills the adult worms or impairs their reproductive capabilities, and the antibiotic doxycycline, which works by killing symbiotic bacteria that live inside the worms, also eliminates adult worms. Albendazole, in combination with others drugs, is being used in a program of mass drug administration undertaken under the auspices of the World Health Organization in an attempt to eliminate filariasis. Begun in 1999 the program treats an entire population in an attempt to eradicate the worm. Control of mosquitoes also is instrumental in holding down the incidence of the disease. Careful hygiene and other measures that prevent and control subsequent bacterial and fungal infections in limbs or genitals in which the lymphatic system has been damaged can reduce disfigurement and suffering. Blocking of the lymph channels and elephantiasis can also result from lymphogranuloma venereum, a sexually transmitted disease.
"elephantiasis." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. (May 28, 2017). http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/elephantiasis
"elephantiasis." The Columbia Encyclopedia, 6th ed.. . Retrieved May 28, 2017 from Encyclopedia.com: http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/elephantiasis
Elephantiasis (el-e-fan-TY-a-sis) is the result of a tropical worm infection called filariasis (fil-a-RY-a-sis). When infected mosquitoes transmit the parasitic worm Wuchereria bancrofti to people, the worm blocks the lymphatic system. The blockage causes swelling in the legs or other parts of the body, making these body parts appear large and puffy, or elephant-like. Elephantiasis is not “elephant man disease,” which is an inherited condition with completely different causes and symptoms.
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Elephantiasis was known to the early Greeks and Romans. It is a tropical or subtropical disease, occurring where many kinds of disease-carrying mosquitoes are found: South America, Cuba, Puerto Rico, West Indies, Africa, Spain, Turkey, Asia, Australia, and many South Pacific Islands. About 100 million people worldwide are affected.
Insects that carry diseases are known as vectors*, and several species of mosquito are vectors of Wuchereria bancrofti, the nematode worm that causes elephantiasis. When a Culex (KYU-lex), Anopheles (a-NOF-e-LEEZ), Aedes (ay-EE-deez), or Mansonia (man-SO-ne-a) mosquito carrying the Wuchereria bancrofti organism bites a human, the mosquito may inject worm larvae* into the body. The tiny larvae then may make their way into the lymph glands and the lymphatic system.
- * vectors
- are animals or insects that carry diseases and transfer them from one host to another.
- * larvae
- are worms at an intermediate stage of the life cycle between egg and adult.
The lymphatic system is a complicated network of very fine tubes, about the diameter of a needle, which criss-cross body tissues to collect a fluid known as lymph. Lymph is a milk-like substance (containing white blood cells, proteins, and fats) that plays an important role in absorbing fats from the intestine, in fighting infections, and in the proper functioning of the immune system. Lymph is returned to the bloodstream via many vessels known as lymphatics. At various points, the lymphatics drain into masses of tissue known as lymph nodes or glands. If a blockage occurs, fluid may collect in the tissues, causing a type of swelling known as lymphedema (limf-e-DEE-ma). In the lymph system draining the legs, for example, few connections exist, and the legs often are a site of swelling when lymphedema occurs.
Worm larvae that make their way into lymph vessels can mature into adult worms. Male worms are long and slender, about 4 to 5 cm long, and 0.1 mm in diameter. Female worms are much larger, 6 to 10 cm long, and about three times wider than the males. The adults make their home mostly near the lymph glands in the lower part of the body. The adult female releases eggs enclosed within an egg membrane (microfllariae), and the microfllariae (mi-kro-fi-LAR-ee-i) develop into larvae to continue the life cycle.
In most parts of the world, microfllariae are at their peak in the blood during the night. The worms restrict the normal flow of lymph, resulting in swelling, thickening of the skin, and discoloration. This is what can cause the appearance of an elephant’s leg. However, the swelling of elephantiasis usually does not occur until a person has been bitten by the disease-carrying mosquitoes many times and has had years of exposure to infected mosquitoes.
In addition to the characteristic swelling, people with this disorder sometimes have bouts of fever and headache. Sometimes their swollen limbs become infected.
Microfilariae sometimes can be seen in blood under a microscope. Often the doctor diagnoses the disorder based on the symptoms and a medical history, after ruling out other disorders with similar symptoms.
The Elephant Man
Joseph “John” Cary Merrick was known as the Elephant Man, but he did not have elephantiasis.
Born in 1862 in Leicester, England, Merrick became a human attraction in circus side shows. His appearance was normal at birth, but when he was about age 5, he developed extensive overgrowths of skin that affected his face, head, torso, arms, and legs. He was reported to have had a 12-inch wrist and a fin-like hand.
For many years, researchers believed that Merrick had neurofibromatosis (neur-o-fib-ro-ma-TO-sis), a genetic condition that causes large growths on the skin and in tissues. Recent research using x-ray studies, however, suggests that Merrick in fact had Proteus syndrome, a condition so rare that only 100 cases in history have been reported.
Medications are not very effective against adult worms. New microfllariae produced by the adult worms often continue to show up months after treatment.
Because elephantiasis is found mainly in poorer countries, money for research into the cure and prevention of the disease has been limited. Effective treatment and preventive efforts would include:
- spraying to kill mosquitoes
- giving antibiotics to prevent infection
- giving medications to kill microfllariae circulating in the blood
- applying pressure bandages to reduce swelling
- surgically removing infected tissue.
World Health Organization, Avenue Appia 20, 1211 Geneva 27, Switzerland. WHO posts a fact sheet about lymphatic filariasis at its website. http://www.who.org/home/map_ht.html
"Elephantiasis." Complete Human Diseases and Conditions. . Encyclopedia.com. (May 28, 2017). http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/elephantiasis
"Elephantiasis." Complete Human Diseases and Conditions. . Retrieved May 28, 2017 from Encyclopedia.com: http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/elephantiasis
"elephantiasis." A Dictionary of Nursing. . Encyclopedia.com. (May 28, 2017). http://www.encyclopedia.com/caregiving/dictionaries-thesauruses-pictures-and-press-releases/elephantiasis
"elephantiasis." A Dictionary of Nursing. . Retrieved May 28, 2017 from Encyclopedia.com: http://www.encyclopedia.com/caregiving/dictionaries-thesauruses-pictures-and-press-releases/elephantiasis
el·e·phan·ti·a·sis / ˌeləfənˈtīəsis/ • n. Med. a condition in which a limb or other part of the body becomes grossly enlarged due to obstruction of the lymphatic vessels, typically by the nematode parasites that cause filariasis.
"elephantiasis." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. (May 28, 2017). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/elephantiasis-0
"elephantiasis." The Oxford Pocket Dictionary of Current English. . Retrieved May 28, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/elephantiasis-0
"elephantiasis." World Encyclopedia. . Encyclopedia.com. (May 28, 2017). http://www.encyclopedia.com/environment/encyclopedias-almanacs-transcripts-and-maps/elephantiasis
"elephantiasis." World Encyclopedia. . Retrieved May 28, 2017 from Encyclopedia.com: http://www.encyclopedia.com/environment/encyclopedias-almanacs-transcripts-and-maps/elephantiasis
"elephantiasis." Oxford Dictionary of Rhymes. . Encyclopedia.com. (May 28, 2017). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/elephantiasis
"elephantiasis." Oxford Dictionary of Rhymes. . Retrieved May 28, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/elephantiasis