Skip to main content
Select Source:

Brucellosis

Brucellosis

Definition

Brucellosis is a bacterial disease caused by members of the Brucella genus that can infect humans but primarily infects livestock. Symptoms of the disease include intermittent fever, sweating, chills, aches, and mental depression. The disease can become chronic and recur, particularly if untreated.

Description

Also known as undulant fever, Malta fever, Gibraltar fever, Bang's disease, or Mediterranean fever, brucellosis is most likely to occur among those individuals who regularly work with livestock. The disease originated in domestic livestock but was passed on to wild animal species, including the elk and buffalo of the western United States. In humans, brucellosis continues to be spread via unpasteurized milk obtained from infected cows or through contact with the discharges of cattle and goats during miscarriage. In areas of the world where milk is not pasteurized, for example in Latin America and the Mediterranean, the disease is still contracted by ingesting unpasteurized dairy products. However, in the United States, the widespread pasteurization of milk and nearly complete eradication of the infection from cattle has reduced the number of human cases from 6,500 in 1940 to about 70 in 1994.

Causes and symptoms

The disease is caused by several different species of parasitic bacteria of the genus Brucella. B. abortus is found in cattle and can cause cows to abort their fetuses. B. suis is most often found in hogs and is more deadly when contracted by humans than the organism found in cattle. B. melitensis is found in goats and sheep and causes the most severe illness in humans. B. rangiferi infects reindeer and caribou, and B. canis is found in dogs.

A human contracts the disease by coming into contact with an infected animal and either allowing the bacteria to enter a cut, breathing in the bacteria, or by consuming unpasteurized milk or fresh goat cheese obtained from a contaminated animal. In the United States, the disease is primarily confined to slaughterhouse workers.

Scientists do not agree about whether brucellosis can be transmitted from one person to another, although some people have been infected from a tainted blood transfusion or bone marrow transplant. Newborn babies have also contracted the illness from their mothers during birth. Currently, it is believed that brucellosis can also be transmitted sexually.

The disease is not usually fatal, but the intermittent fevers (a source of its nickname, "undulant fever") can be exhausting. Symptoms usually appear between five days and a month after exposure and begin with a single bout of high fever accompanied by shivering, aching, and drenching sweats that last for a few days. Other symptoms may include headache, poor appetite, backache, weakness, and depression. Mental depression can be so severe that the patient may become suicidal.

KEY TERMS

Antibody A specific protein produced by the immune system in response to a specific foreign protein or particle called an antigen.

Chronic Disease or condition characterized by slow onset over a long period of time.

Parasite An organism living in or on, and obtaining nourishment from, another organism.

Pasteurization The process of applying heat, usually to milk or cheese, for the purpose of killing, or retarding the development of, pathogenic bacteria.

In rare, untreated cases, the disease can become so severe that it leads to fatal complications, such as pneumonia or bacterial meningitis. B. melitensis can cause miscarriages, especially during the first three months of pregnancy. The condition can also occur in a chronic form, in which symptoms recur over a period of months or years.

Diagnosis

Brucellosis is usually diagnosed by detecting one or more Brucella species in blood or urine samples. The bacteria may be positively identified using biochemical methods or using a technique whereby, if present in the sample, the brucellosis bacteria are made to fluoresce. Brucellosis may also be diagnosed by culturing and isolating the bacteria from one of the above samples. Blood samples will also indicate elevated antibody levels or increased amounts of a protein produced directly in response to infection with brucellosis bacteria.

Treatment

Prolonged treatment with antibiotics, including tetracyclines (with streptomycin), co-trimoxazole, and sulfonamides, is effective. Bed rest is also imperative. In the chronic form of brucellosis, the symptoms may recur, requiring a second course of treatment.

Prognosis

Early diagnosis and prompt treatment is essential to prevent chronic infection. Untreated, the disease may linger for years, but it is rarely fatal. Relapses may also occur.

Prevention

There is no human vaccine for brucellosis, but humans can be protected by controlling the disease in livestock. After checking to make sure an animal is not already infected, and destroying those that are, all livestock should be immunized. Butchers and those who work in slaughterhouses should wear protective glasses and clothing, and protect broken skin from infection.

Some experts suggest that a person with the disease refrain from engaging in unprotected sex until free of the disease. The sexual partners of an infected person should also be closely monitored for signs of infection.

Resources

ORGANIZATIONS

Centers for Disease Control and Prevention. 1600 Clifton Rd., NE, Atlanta, GA 30333. (800) 311-3435, (404) 639-3311. http://www.cdc.gov.

OTHER

"Bacterial Diseases." Healthtouch Online Page. http:www.healthtouch.com.

Centers for Disease Control. http://www.cdc.gov/nccdphp/ddt/ddthome.htm.

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

  • MLA
  • Chicago
  • APA

"Brucellosis." Gale Encyclopedia of Medicine, 3rd ed.. . Encyclopedia.com. 27 Jun. 2017 <http://www.encyclopedia.com>.

"Brucellosis." Gale Encyclopedia of Medicine, 3rd ed.. . Encyclopedia.com. (June 27, 2017). http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/brucellosis

"Brucellosis." Gale Encyclopedia of Medicine, 3rd ed.. . Retrieved June 27, 2017 from Encyclopedia.com: http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/brucellosis

Brucellosis

Brucellosis

Brucellosis is a disease caused by bacteria in the genus Brucella. The disease infects animals such as swine, cattle, and sheep; humans can become infected indirectly through contact with infected animals or by drinking Brucella-contaminated milk. In the United States, most domestic animals are vaccinated against the bacteria, but brucellosis remains a risk with imported animal products.

Brucella are rod-shaped bacteria that lack a capsule around their cell membranes. Unlike most bacteria, Brucella cause infection by actually entering host cells. As the bacteria cross the host cell membrane, they are engulfed by host cell vacuoles called phagosomes. The presence of Brucella within host cell phagosomes initiates a characteristic immune response, in which infected cells begin to stick together and form aggregations called granulomas.

Three species of Brucella cause brucellosis in humans: Brucella melitensis, which infects goats; B. abortis, which infects cattle and, if the animal is pregnant, causes the spontaneous abortion of the fetus; and B. suis, which infects pigs. In animals, brucellosis is a self-limiting disease, and usually no treatment is necessary for the resolution of the disease. However, for a period of time from a few days to several weeks, infected animals may continue to excrete brucella into their urine and milk. Under warm, moist conditions, the bacteria may survive for months in soil, milk, and even seawater.

Because the bacteria are so hardy, humans may become infected with Brucella by direct contact with the bacteria. Handling or cleaning up after infected animals may put a person in contact with the bacteria. Brucella are extremely efficient in crossing the human skin barrier through cuts or breaks in the skin.

The incubation period of Brucella, the time from exposure to the bacteria to the start of symptoms, is typically about three weeks. The primary complaints are weakness and fatigue. An infected person may also experience muscle aches, fever, and chills.

The course of the disease reflects the location of the Brucella bacteria within the human host. Soon after the Brucella are introduced into the bloodstream, the bacteria seek out the nearest lymph nodes and invade the lymph node cells. From the initial lymph node, the Brucella spread out to other organ targets, including the spleen, bone marrow, and liver. Inside these organs, the infected cells form granulomas.

Diagnosing brucellosis involves culturing the blood, liver, or bone marrow for Brucella organisms. A positive culture alone does not signify brucellosis, since persons who have been treated for the disease may continue to harbor Brucella bacteria for several months. Confirmation of brucellosis, therefore, includes a culture positive for Brucella bacteria as well as evidence of the characteristic symptoms and a history of possible contact with infected milk or other animal products.

In humans, brucellosis caused by B. abortus is a mild disease that resolves itself without treatment. Brucellosis caused by B. melitensis and B. suis, however, can be chronic and severe. Brucellosis is treated with administration of an antibiotic that penetrates host cells to destroy the invasive bacteria.

Since the invention of an animal vaccine for brucellosis in the 1970s, the disease has become somewhat rare in the United States. Yet the vaccine cannot prevent all incidence of brucellosis. The Centers for Disease Control usually reports fewer than 100 total cases per year in the United States. Most of these were reported in persons who worked in the meat processing industry. Brucellosis remains a risk for those who work in close contact with animals, including veterinarians, farmers, and dairy workers.

Brucellosis also remains a risk when animal products from foreign countries are imported into the United States. Outbreaks of brucellosis have been linked to unpasteurized feta and goat cheeses from the Mediterranean region and Europe. In the 1960s, brucellosis was linked to bongo drums imported from Africa; drums made with infected animal skins can harbor Brucella bacteria, which can be transmitted to humans through cuts and scrapes in the human skin surface.

In the United States, preventive measures include a rigorous vaccination program that involves all animals in the meat processing industry. On an individual level, people can avoid the disease by not eating animal products imported from countries where brucellosis is frequent, and by avoiding foods made with unpasteurized milk.

See also Bacteria and bacterial infection; Food safety; Infection and resistance; Pasteurization

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

  • MLA
  • Chicago
  • APA

"Brucellosis." World of Microbiology and Immunology. . Encyclopedia.com. 27 Jun. 2017 <http://www.encyclopedia.com>.

"Brucellosis." World of Microbiology and Immunology. . Encyclopedia.com. (June 27, 2017). http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/brucellosis

"Brucellosis." World of Microbiology and Immunology. . Retrieved June 27, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/brucellosis

Brucellosis

BRUCELLOSIS

Brucellosis, a zoonosis, is a bacterial infection, mainly of cows and goats, but with humans as alternative hosts. The causative organisms, Brucella abortus or Brucella melitensis, are small gram-negative bacilli that are difficult to cultivate, though they can be isolated from blood culture in the acute and sometimes in the chronic phase. Varieties of the causative organisms (e.g., B. canis and B. suis ) occur in every part of the world where domesticated and wild cattle or goats are found. Brucellosis responds to treatment with antibiotics such as rifampin and streptomycin.

Humans are usually infected by handling or eating infected animal parts or dairy products. Person-to-person transmission does not occur. Brucellosis is principally an occupational disease of goat and cattle farmers, veterinarians, and abattoir workers. It has always been prevalent in countries around the Mediterranean Seawhere it was formerly called undulant, Mediterranean, or Malta feverbut it can occur wherever there are herds of cattle or goats. It may have an acute or insidious onset following an incubation period of up to two months, and it frequently lingers for many months or even yearssometimes for the remainder of a person's lifewith remissions and relapses of low fever, debility, depression, weight loss, joint pains and arthritis, and sometimes enlargement of the spleen and liver.

In 1859, Florence Nightingale, previously a very active woman, returned unwell to England from the Crimean War, where she had established a hospital for sick and injured soldiers. She remained a chronic invalid until her death in 1910, probably suffering from brucellosis.

Besides its debilitating and (rarely) fatal effects on human victims, brucellosis has considerable economic importance because it causes abortion in dairy cattle (hence the name of the commonest variety of the causative organism, which also carries the name of its discoverer, Sir David Bruce).

When brucellosis is diagnosed in a domestic animal herd, segregation of the herd is mandatory. Sometimes the herd is slaughtered and incinerated. Prevention of transmission depends on education of workers, scrupulous hygiene, avoidance of contact with suspected infected animal parts, especially the placenta, and the use of serologic tests to identify infected animals. Preventing infection of occupationally exposed humans also relies mainly on education, personal hygiene, and avoidance of contact with contaminated animals and their carcases. Pasteurization of milk and dairy products protects against infection by the ingestion of such products.

John M. Last

(see also: Veterinary Public Health; Zoonoses )

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

  • MLA
  • Chicago
  • APA

"Brucellosis." Encyclopedia of Public Health. . Encyclopedia.com. 27 Jun. 2017 <http://www.encyclopedia.com>.

"Brucellosis." Encyclopedia of Public Health. . Encyclopedia.com. (June 27, 2017). http://www.encyclopedia.com/education/encyclopedias-almanacs-transcripts-and-maps/brucellosis

"Brucellosis." Encyclopedia of Public Health. . Retrieved June 27, 2017 from Encyclopedia.com: http://www.encyclopedia.com/education/encyclopedias-almanacs-transcripts-and-maps/brucellosis

brucellosis

brucellosis (brōō´səlō´sĬs) or Bang's disease, infectious disease of farm animals that is sometimes transmitted to humans. In humans the disease is also known as undulant fever, Mediterranean fever, or Malta fever. In susceptible animals, primarily cattle, swine, and goats, brucellosis causes infertility and death. The symptoms are spontaneous abortion and inability to conceive in females and inflammation of sex organs in male animals. Animal brucellosis is transmitted by contact or by such mechanical vectors as contaminated food, water, and excrement. The disease is caused by three species of Brucella bacteria, and the causative organism is present in aborted fetuses and uterine secretions; antibodies to the bacteria are present in the blood or milk, an important diagnostic factor. Measures for prevention and control of brucellosis include vaccination of calves, blood tests of adults, and slaughtering of infected animals. Human brucellosis is an occupational disease among farmers, slaughterhouse workers, and others who come in direct contact with infected animals or their products (raw meat or unpasteurized dairy products). The most prominent symptoms are weakness and intermittent fever. The disease persists for months if left untreated but is seldom fatal in humans. There is no effective vaccine for human brucellosis, and antibiotics are the usual treatment.

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

  • MLA
  • Chicago
  • APA

"brucellosis." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. 27 Jun. 2017 <http://www.encyclopedia.com>.

"brucellosis." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. (June 27, 2017). http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/brucellosis

"brucellosis." The Columbia Encyclopedia, 6th ed.. . Retrieved June 27, 2017 from Encyclopedia.com: http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/brucellosis

brucellosis

brucellosis (Malta fever, Mediterranean fever, undulant fever) (broo-si-loh-sis) n. a chronic disease of farm animals caused by bacteria of the genus Brucella, which can be transmitted to humans either by contact with an infected animal or by drinking nonpasteurized contaminated milk. Symptoms include headache, fever, aches and pains, and sickness; occasionally a chronic form develops with recurrent symptoms.

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

  • MLA
  • Chicago
  • APA

"brucellosis." A Dictionary of Nursing. . Encyclopedia.com. 27 Jun. 2017 <http://www.encyclopedia.com>.

"brucellosis." A Dictionary of Nursing. . Encyclopedia.com. (June 27, 2017). http://www.encyclopedia.com/caregiving/dictionaries-thesauruses-pictures-and-press-releases/brucellosis

"brucellosis." A Dictionary of Nursing. . Retrieved June 27, 2017 from Encyclopedia.com: http://www.encyclopedia.com/caregiving/dictionaries-thesauruses-pictures-and-press-releases/brucellosis