Trypanosomiasis is a mastigophora (a type of protozoa) infection caused by one of three species of the genus Trypanosoma. T. brucei gambiense and T. brucei rhodesiense cause African sleeping sickness while T. cruzi causes South American sleeping sickness, or Chagas’ disease.
There are five closely related variants of the trypanosomes in Africa – Trypanosoma gambiense and T. rhodesiense, which affect humans; T. gongolense, T. vivax, and T. brucei, which affect livestock. All sail uninhibited through the bloodstream. Trypanosomes in the blood double every five to ten hours. At least every six minutes a cell with a completely different coat pops up, allowing the organism to avoid detection by the immune system. By the time the immune system has identified the new strain and developed antibodies to combat it, these single-celled parasites have switched again, renewing their efforts in producing weeks of illness.
The tsetse fly is the carrier for the African sleeping sickness. Cattle, swine, and various wild animals are the natural hosts for the protozoa. Humans acquire the disease when a tsetse fly bites an infected animal and then a human. When a person is bitten, the trypanosomes cause a local lesion at the site of the bite. The protozoa then spread and become lodged in the lymph nodes, producing chronic infection. In some cases, the trypanosomes spread to the CNS (central nervous system), which results in the characterized symptoms of sleeping sickness.
T. cruzi, related to T. brucei, was first reported in Latin America and seemed to be a parasite looking for a disease. It finally accomplished its desire in a remote village north of Rio de Janeiro, where workers were building the Central Brazilian Railway. When researchers went in, they found the cause to be the reduviid bug (kissing bugs), a roach-like insect, that lives in the thatched roofs and cracks in the walls. At night, they would emerge and feed on the sleeping workers (usually around the mouth, thus the name of kissing bug), leaving its feces at the scene to be scratched into the bloodstream or be carried into the mouth, nose, or eyes. Acute infections often involve children, who go on to have problems with their heart and CNS, with a mortality rate of about 10%. There is really no effective treatment, and drugs have little effect on the parasite. Obviously, there can be no vaccine since it mutates so quickly. Estimates of infection range from ten to eighteen million Latin Americans. Once only a disease of the poor, it has found its way into all social classes. Recently, it has been found in the US blood banks.
