Trypanosomiasis, American (Chagas Disease)
The protozoan parasite Trypanosoma cruzi.
Typically through feces of an infected triatomine insect (reduviid bug). Infection 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, organ transplantation, or from mother to infant.
Endemic to many parts of Mexico and Central and South America; rare locally acquired cases reported in the southern United States. No vectorborne transmission has been documented in the Caribbean islands. 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 (indurated local swelling) may develop at the site of infection (such as 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 infected people develop chronic manifestations after a prolonged asymptomatic period. Chronic Chagas disease usually affects the heart; clinical signs include conduction system abnormalities, ventricular arrhythmias, and in late-stage disease, congestive cardiomyopathy. Chronic gastrointestinal problems (such as megaesophagus or megacolon) are less common and 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 with chronic infection, treatment is usually recommended.
The 2 drugs used to treat Chagas disease are nifurtimox and benznidazole. Benznidazole is approved by FDA for use in children 2–12 years of age and is commercially available (see www.cdc.gov/parasites/chagas/health_professionals/tx.html for more information). Nifurtimox is not currently FDA approved. Nifurtimox is available under an investigational protocol from CDC. Side effects are common with both drugs and tend to be more frequent and more severe with increasing age. Contact CDC (firstname.lastname@example.org; 404-718-4745) for assistance with clinical management.
Insect precautions (see Chapter 3, 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; use insecticides in and around such homes. Insecticide-treated bed nets are helpful. Screening blood and organs for Chagas disease prevents transmission via transfusion or transplantation.
CDC website: www.cdc.gov/parasites/chagas
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Susan Montgomery, Sharon L. Roy, Christine Dubray