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Category: Clinical Microbiology
Trypanosomiasis, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555816018/9781555813802_Chap09-1.gif /docserver/preview/fulltext/10.1128/9781555816018/9781555813802_Chap09-2.gifAbstract:
Human infections are caused by Trypanosoma brucei gambiense (West African trypanosomiasis) and Trypanosoma brucei rhodesiense (East African trypanosomiasis). Trypanosomes infecting humans in the Americas belong to the subgenus Tejaraia (Trypanosoma rangeli) and Schizotrypanum (Trypanosoma cruzi). T. rangeli infections are asymptomatic, with no evidence of pathology; however, T. cruzi infections (American trypanosomiasis) can cause considerable morbidity and mortality. A simple and rapid test, the card indirect agglutination trypanosomiasis test, is available, primarily in areas of endemic infection, for the detection of circulating antigens in persons with African trypanosomiasis. Accurate identification of trypanosome species, which is necessary to clarify the epidemiology of human and animal African trypanosomiasis, has been difficult. Great progress has been made over the last 10 years through the application of DNA probe technology, although this has also revealed greater complexity than was previously supposed. The incidence of East African trypanosomiasis is characterized by short epidemics interspersed with long periods of low (often undectable) endemicity. In the chronic stage of Chagas’ disease, trypomastigotes are very rare or absent in the peripheral blood except during febrile exacerbations. Diagnosis depends primarily on culture, xenodiagnosis, or serologic tests. The patient may also be monitored through serologic tests and electrocardiograms. Serologic tests used for the diagnosis of Chagas’ disease include complement fixation, indirect fluorescent-antibody tests, indirect hemagglutination tests, and enzyme-linked immunosorbent assay (ELISA). T. rangeli trypomastigotes can be detected in the peripheral blood by using thin and thick blood smears and concentration techniques.
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Distribution of trypanosomes in Africa. (Armed Forces Institute of Pathology photograph.)
Life cycle stages of trypanosomes. Amastigotes have been confirmed in the life cycle of Trypanosoma cruzi as one of the stages in the human host, but this stage in humans in African trypanosomiasis is only suspected and not confirmed. (Illustration by Nobuko Kitamura.)
Life cycle of Trypanosoma brucei gambiense and T. brucei rhodesiense.
Trypanosoma brucei gambiense trypomastigotes in peripheral blood smears. Note the small kinetoplast.
Winterbottom’s sign (enlarged cervical lymph nodes in the posterior cervical triangle). (Armed Forces Institute of Pathology photograph.)
Coronal section of brain showing congested white matter and petechial hemorrhages. (Armed Forces Institute of Pathology photograph.)
Morular cell in the hypothalamus. (Armed Forces Institute of Pathology photograph.)
Close-up view of the meninges showing a morular cell. (Armed Forces Institute of Pathology photograph.)
African trypanosomiasis.
Life cycle of Trypanosoma cruzi.
(Top and middle) Trypanosoma cruzi trypomastigotes in a peripheral blood smear. Note the large kinetoplast. (Bottom) Scanning electron micrograph of a trypomastigote of T. cruzi. (Bottom photograph courtesy of David T. John.)
Trypanosoma cruzi amastigotes in cardiac muscle.
Epimastigotes of Trypanosoma cruzi.
(Upper) Female child with Romaña’s sign. (Armed Forces Institute of Pathology photograph.) (Lower) Male child with Romaña’s sign. (From A Pictorial Presentation of Parasites: A cooperative collection prepared and/or edited by H. Zaiman.)
An enlarged heart in a 46-year-old man 13 days after onset of acute Chagas’ disease. (Armed Forces Institute of Pathology photograph.)
Acute chagasic myocarditis. (Original photograph by B. H. Kean; from A Pictorial Presentation of Parasites: A cooperative collection prepared and/or edited by H. Zaiman.)
Open chagasic heart with thinning of wall. (Original photograph by B. H. Kean; from A Pictorial Presentation of Parasites: A cooperative collection prepared and/or edited by H. Zaiman.)
(Top) Posterior half of a heart with chronic chagasic cardiopathy. Note the left ventricle dilation and apical aneurysm. (Armed Forces Institute of Pathology photograph.) (Middle) Aneurysmal dilatation and thinning of the apical myocardium, plus marked concentric muscular hypertrophy. (Bottom) Same heart with thin apical myocardium. Note the light shining through the thinned muscle. (Middle and bottom photographs by J. H. Edgecome; from A Pictorial Presentation of Parasites: A cooperative collection prepared and/or edited by H. Zaiman.)
Chagasic megaesophagus. (Original photography by D. N. Reifsnyder; from A Pictorial Presentation of Parasites: A cooperative collection prepared and/or edited by H. Zaiman.)
Megacolon in an adult male with Chagas’ disease. (Armed Forces Institute of Pathology photograph.)
American trypanosomiasis.
Life cycle of Trypanosoma rangeli.
Trypanosoma rangeli trypomastigote in a peripheral blood smear. Note the small kinetoplast. (Armed Forces Institute of Pathology photograph.)
Classification of trypanosomes infecting humans
Characteristics of East and West African trypanosomiasis
Methods available for the diagnosis of African trypanosomiasis (T. brucei gambiense)
Methods available for the diagnosis of African trypanosomiasis (T. brucei rhodesiense)
Characteristics of American trypanosomiais
Trypanosoma cruzi: principal vectors