Typically through feces of an infected triatomine insect (reduviid bug), may occur when a bug bite is scratched or by consuming food or beverages contaminated with infected bug feces; may also be transmitted through blood transfusion or organ transplantation and from mother to infant.
Endemic in many parts of Mexico and Central and South America. In the United States, Chagas disease is primarily a disease of immigrants from endemic areas of Latin America. The risk to travelers is extremely low, but they could be at risk if staying in poor-quality housing or from consuming contaminated food or beverages in endemic areas.
Acute illness typically develops ≥1 week after exposure and lasts up to 60 days. A chagoma may develop at the site of infection; for example, the Romaña sign (edema of the eyelid and ocular tissues). Most infected people never develop symptoms but remain infected throughout their lives. Approximately 20%–30% of patients will develop chronic manifestations of Chagas disease after a prolonged period without any clinical disease. Chronic Chagas disease usually affects the heart; clinical signs include conduction system abnormalities, ventricular arrhythmias, and in late-stage disease, congestive cardiomyopathy. Less common chronic gastrointestinal problems (such as megaesophagus or megacolon) may develop with or without cardiac manifestations. Reactivation disease can occur in immunocompromised patients.
During the acute phase, parasites may be detectable in fresh preparations of buffy coat or stained peripheral blood specimens; PCR testing may also help detect acute infection. After the acute phase, diagnosis requires 2 or more serologic tests (most commonly, ELISA, immunoblot, and immunofluorescent antibody test) to detect T. cruzi–specific antibodies. PCR is not a useful diagnostic test for chronic-phase infections since parasites are not detectable in the peripheral blood during this phase.
Antitrypanosomal drug treatment is always recommended for acute, early congenital, and reactivated T. cruzi infection and for chronic T. cruzi infection in children aged <18 years old. In adults, treatment is usually recommended. In the United States, treatment drugs (benznidazole and nifurtimox) are provided by CDC under investigational protocols. Contact CDC (chagas@cdc. gov; 404-718-4745) for assistance with clinical management.
Insect precautions (see Chapter 2, Protection against Mosquitoes, Ticks, & Other Arthropods) and food and water precautions (see Chapter 2, Food & Water Precautions). Avoid sleeping in thatch, mud, and adobe housing in endemic areas; using insecticides in and around such homes is also protective. Impregnated bed nets are helpful. Screening blood and organs for Chagas disease prevents transmission via transfusion or transplantation.
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Bern C, Montgomery SP, Herwaldt BL, Rassi A Jr, Marin-Neto JA, Dantas RO, et al. Evaluation and treatment of Chagas disease in the United States: a systematic review. JAMA. 2007 Nov 14;298(18):2171–81.
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Rassi A Jr, Rassi A, Marin-Neto JA. Chagas disease. Lancet. 2010 Apr 17;375(9723):1388–402.