trypanosomiasis(redirected from African lethargy)
Also found in: Dictionary, Medical.
trypanosomiasis (trəpănˌəsōmīˈəsis), infectious disease caused by a protozoan organism, the trypanosome, which exists as a parasite in the blood of a number of vertebrate hosts. The three variations of the disease that predominate in humans are transmitted by an insect vector. Two types of African sleeping sickness are caused, respectively, by Trypanosoma brucei rhodesiense and T. brucei gambiense, both transmitted by the bite of the tsetse fly. South American trypanosomiasis, or Chagas' disease, is caused by T. cruzi, which is the most common cause of heart disease in South America. It is transmitted by certain species of bugs; the parasite enters the skin when infected bug feces are rubbed into the site of the bite.
The characteristic symptoms of Chagas' disease are edema; hard, red nodular outbreaks of the skin; and damage to the heart muscle. There is no effective treatment. Symptoms of African sleeping sickness may appear at once, after several weeks, or even after years in the Gambian type, which is the most common form. Early disturbances include inflammation at the site of the bite, intermittent fever, enlargement of the spleen; in the Gambian variety the lymph nodes are enlarged. Subsequent signs of heart damage, personality changes, and headache develop. The final stages are marked by tremor, disturbed speech and gait, emaciation, and a prolonged comatose state. African trypanosomiasis is treated with pentamidine or suramin, which are effective when injected in early stages of the disease; in the second stage, when the nervous system is affected, treatment involves melarsoprol or nifurtimox and eflornithine. Even with treatment, organ damage appears irreversible and the disease is often fatal; the prognosis becomes grave after the nervous system is invaded. Prevention involves the use of insecticides and the clearing of vegetation that harbors the tsetse fly. A form of trypanosomiasis known as nagana affects cattle, leading to enormous annual economic losses.
a disease of man and animals caused by members of the genus of protozoans trypanosoma. Trypanoso-miasis is a naturally endemic transmissible disease. Diseased persons and animals are sources of infection. Two forms of trypano-somiasis have been observed in man: African sleeping sickness and Chagas’ disease (American trypanosomiasis). Prevention includes the destruction of transmitters (insects) and chemopro-phylaxis of humans.
Trypanosomiasis of animals is widely prevalent in Africa, Central and South America, and Asia. It causes great damage to livestock. Forms found in the USSR include dourine of equids and su-auru of camels, horses, donkeys, mules, and dogs. The principal causative agents of trypanosomiasis of domestic animals are Trypanosoma brucei, T. vivax, T. congolense, T. simiae, T. evansi, and T. equiperdum. All species of vertebrates are affected. The causative agents are transmitted by biological vectors, mainly tsetse, lice, mites, ticks, and fleas; by mechanical means, for example, by horseflies and mosquitoes; or by sexual contact, in the case of dourine. Carnivores and omnivores may become infected by eating the flesh of diseased animals. Large wild animals and biological vectors play an important part in spreading and preserving the causative agents.
Symptoms include intermittent fever, inhibition, lacrimation, edema, and paresis and paralysis of the extremities. Trypano-somes are occasionally found in the peripheral blood when symptoms appear. Animals usually die as a result of paralysis if the course of the disease is acute or subacute and as a result of cachexia if it is chronic. The diagnosis is based on epizootological data, symptoms, presence of the causative agent in the blood, and results of sérologie tests. The disease is treated with such trypanocides as naganin, Pyraldin (Antrycide), omidium salts, and Azidin. Preventive measures include the control of vectors, treatment of animals with trypanocides, and detection and treatment of all parasite carriers.