What is trypanosomiasis?

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Trypanosomiasis is a tropical parasitic disease transmitted by the African tsetse fly, which infects the blood, lymphatic system, and nervous system in humans and animals.
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Definition

Trypanosomiasis is a tropical parasitic disease transmitted by the African tsetse fly, which infects the blood, lymphatic system, and nervous system in humans and animals.

Causes

Trypanosomiasis is caused by a bite from the tsetse fly, an insect found only in sub-Saharan Africa. This fly conveys the Trypanosoma parasite. Trypanosomiasis also can be transferred through the placenta during pregnancy. Additionally, laboratory workers have become infected with trypanosomiasis by accidentally pricking their skin with needles infected with Trypanosoma.

Risk Factors

Because the vector of trypanosomiasis, the tsetse fly, is found only in rural areas of sub-Saharan Africa, those who frequent those areas, and villagers, hunters, and fishermen, are at greatest risk. Persons inhabiting rural African woodland and savannah regions, especially near bodies of water and dense vegetation, are most susceptible.

Symptoms

The symptoms of trypanosomiasis include fever, headaches, swollen lymph nodes, extreme fatigue, skin rash, itching, joint and muscle pain, weight loss, confusion, sleepiness, slurred speech, impaired coordination, and altered personality.

Screening and Diagnosis

After conducting a physical examination and after questioning the patient about symptoms and medical history, a physician will draw blood and spinal fluid samples. Electron microscopy of spinal fluid is necessary to confirm a diagnosis of trypanosomiasis because trypanosomiasis frequently is asymptomatic or manifests mild symptoms in its initial stage, and because it is sometimes difficult to discern in blood.

Treatment and Therapy

Five drugs are used to treat trypanosomiasis, depending upon the stage of the illness. Suramin and pentamidine are used to treat trypanosomiasis in its initial stage, when it is confined to the blood and lymphatic systems. If trypanosomiasis is advanced and has infected the nervous system, then melarsoprol or eflornithine, sometimes combined with nifurtimox, is administered in a hospital setting. For two years after treatment, at six-month intervals, the patient’s spinal fluid is drawn and tested for trypanosomiasis because the patient may relapse or become reinfected, requiring further treatment.

Prevention and Outcomes

The World Health Organization has greatly reduced trypanosomiasis by treating male tsetse flies with radiation—rendering them sterile—then releasing them back into the environment, thereby lowering the number of tsetse flies. Although there is no vaccine or drug that prevents trypanosomiasis, several steps may be taken to reduce the likelihood of infection. In endemic areas, one should use netting or screens around tents or other living areas to barricade against insects. All skin, wherever possible, should be covered by medium-weight clothing to protect against insect bites. Bright and dark colors should be avoided because tsetse flies are attracted to those colors; one should instead wear light colors.

Tsetse flies bite during the daytime, but they repose in bushes during the hottest part of the day, so bushes and dense vegetation should be avoided if possible. Because tsetse flies are attracted to swirling dust created by moving vehicles on the African savannah, vehicles should be examined carefully for tsetse flies before being entered.

Bibliography

Dumas, Michel, Bernard Bouteille, and Alain Buguet, eds. Progress in Human African Trypanosomiasis, Sleeping Sickness. New York: Springer, 1999.

Kruel, Donald. Deadly Diseases and Epidemics: Trypanosomiasis. New York: Chelsea House, 2007.

Maudlin, I., P. H. Holmes, and M. A. Miles, eds. The Trypanosomiases. Cambridge, Mass.: CABI, 2004.

World Health Organization. “African Trypanosomiasis (Sleeping Sickness).” Available at http://www.who.int/mediacentre/factsheets/fs259.

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