Trypanosomiasis

Trypanosomiasis (trib-pan-o-so-MY-ub-sis) is a disease found  in Africa and the American continents that is caused by infection with a parasite. Forms of the disease may persist for many years and bave several phases, with symptoms that can vary from one stage to the next.

What Is Trypanosomiasis?

Trypanosomiasis is the name for three types of infections caused by protozoa and spread to humans through insect bites. There are two kinds of African trypanosomiasis, East African and West African. Both of these varieties also are known as sleeping sickness. The disease can affect people living on the African continent south of the Sahara Desert. American trypanosomiasis is also called Chagas' (SHAH-gus) disease. It occurs only on the American continents, from Mexico to Argentina.

What Causes Trypanosomiasis?

The bite of an infected tsetse (SET-see) fly usually transmits the organisms that cause the African forms of trypanosomiasis. These flies live in the countryside in Africa, especially in bushes and thick vegetation near rivers and lakes. Tsetse flies infected with the protozoan Trypanosoma brucei rhodesiense (trih-pan-o-SO-mah BRU-see-eyc ro-dee-see-EN-see) spread East African trypanosomiasis, the most severe form of the disease, to humans. The West African variety comes from a fly infected with Trypanosoma brucei gambiense (trih-pan-o-SO-mah BRU-see-eye gam-be-EN-see).

Reduviid (rih-DO-vee-id) bugs (also called assassin, cone-nose, or kissing bugs) carry the Trypanosoma cruzi (trih-pan-o-SO-mah KROO-zee) protozoa that cause the American variety of trypanosomiasis, or Chagas' disease, named for the Brazilian physician Carlos Chagas (1879-1934) who discovered it in 1909. These bugs hide during the day in the cracks in mud and adobe homes. At night they crawl across sleeping people and bite them, usually on the face but sometimes on the arms, legs, or trunk. They also leave behind their feces*, which contain the protozoa. Without knowing it, people can rub the infected feces into the bite, a cut, or open sore, or even into their noses, mouths, or eyes.

How Common Is Trypanosomiasis?

Trypanosomiasis can infect people of every age and race, although it is uncommon in the United States. Since the late 1960s, fewer than 30 cases have been reported among U.S. citizens traveling to areas where the infection is found. In other parts of the world, however, the disease affects thousands of people. The World Health Organization estimates that as many as 500,000 people could have African trypanosomiasis, but because of poor monitoring most of these cases are not reported.

Between 16 million and 18 million people in the Americas in the early 2000s had Chagas' disease. Approximately 50,000 may die from the disease each year.

Is Trypanosomiasis Contagious?

People cannot catch any form of trypanosomiasis in the same way that they catch a cold or the flu from other people. Only the tsetse fly spreads the African varieties, and the reduviid bug spreads Chagas' disease. Rarely, a mother infected with the West African variety of trypanosomiasis or with Chagas' disease can pass the illness to her unborn child. People who receive a transfusion of blood or an organ transplant from an infected person also may contrat the disease; this form of transmission tends to happen more often with Chagas' disease than with the African types.

What Are the Symptoms of the Disease?

African trypanosomiasis People who contract the African varieties of trypanosomiasis may start sleeping more, although this usually does not happen until the later stages of the disease. Sleeping sickness may start with the appearance of a sore called a chancre (SHANG-ker) at the spot where the person received the tsetse fly bite. Later symptoms include fever, extreme tiredness, severe headaches, rashes, itching, joint pain, and swelling of the hands and feet. The lymph nodes on the back of the neck may become swollen as well. These signs typically appear two to four weeks after infection with East African trypanosomiasis.