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Chagas disease: Natural history and diagnosis

Caryn Bern, MD, MPH
Section Editor
Peter F Weller, MD, MACP
Deputy Editor
Elinor L Baron, MD, DTMH


Chagas disease is caused by infection with the protozoan parasite Trypanosoma cruzi; the major manifestations are Chagas cardiomyopathy and gastrointestinal disease [1]. Issues related to the natural history of infection, diagnosis, and clinical circumstances will be reviewed here. Other issues related to Chagas disease, including cardiac and gastrointestinal involvement, are discussed in detail separately. (See related topics.)


Transmission — Humans and other mammals usually become infected when the triatomine vector defecates during its blood meal, and fecal material containing the parasite is inoculated through the bite wound or mucous membranes [2]. Transmission can also occur congenitally from mother to infant, via transfusion of blood components, via transplantation of an organ from an infected donor, and via consumption of contaminated food or drink. (See "Chagas disease: Epidemiology and control".)

Acute phase — The incubation period following exposure is one to two weeks, after which the acute phase of Chagas disease begins [3]. In the setting of transfusion- and transplant-associated cases, the incubation period may be as long as four months [4,5].

The acute phase of T. cruzi infection lasts 8 to 12 weeks and is characterized by circulating trypomastigotes detectable by microscopy of fresh blood or buffy coat smears (picture 1). Most patients have nonspecific symptoms (such as malaise, fever, and anorexia) or are asymptomatic so do not come to clinical attention during the acute phase.

In a minority of patients, acute infection may be associated with inflammation and swelling at the site of inoculation, known as a chagoma. Chagomas typically occur on the face or extremities; in some cases, parasites can be demonstrated in the lesion. Inoculation via the conjunctiva may lead to a characteristic unilateral swelling of the upper and lower eyelid known as Romaña's sign (picture 2).


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Literature review current through: Jul 2017. | This topic last updated: Feb 09, 2017.
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