Author(s): Susan Montgomery, Sharon Roy, Christine Dubray

Infectious Agent

Chagas disease is caused by the protozoan parasite Trypanosoma cruzi.

Transmission

Human infection occurs when T. cruzi in the feces of an infected triatomine insect (reduviid bug) enters the body. Entry portals include breaks in the skin (e.g., at the site of a reduviid bug bite), through the eyes by touching or rubbing with contaminated fingers, and through the gastrointestinal tract by consuming contaminated food or beverages. T. cruzi also can be transmitted through blood transfusions, organ transplantation, and vertically, from mother to infant.

Epidemiology

T. cruzi is endemic to many parts of Mexico and Central and South America; rare locally acquired Chagas disease cases have been 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 travelers could be at risk if they stay in poor-quality housing or consume contaminated food or beverages in endemic areas.

Clinical Presentation

Acute illness typically develops ≥1 week and ≤60 days after exposure. A chagoma (indurated local swelling) might develop at the site of parasite entry (e.g., Romaña’s 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 (e.g., megaesophagus, megacolon) are less common. and can develop with or without cardiac manifestations. Reactivation disease can occur in immunocompromised patients.

Diagnosis

During the acute phase, parasites can be detected in fresh preparations of buffy coat or stained peripheral blood specimens; PCR testing also can help detect acute infection. After the acute phase, diagnosis requires ≥2 serologic tests to detect T. cruzi–specific antibodies, most commonly ELISA, immunoblot, and immunofluorescent antibody test.

PCR is not a useful diagnostic test for chronic-phase infections because parasites cannot be detected in the peripheral blood during this phase. Clinicians can obtain diagnostic assistance and confirmatory testing from the Centers for Disease Control and Prevention (CDC)’s Division of Parasitic Diseases and Malaria DPDx laboratory (dpdx@cdc.gov), and from the Parasitic Diseases Hotline for Healthcare Providers (404-718-4745; parasites@cdc.gov).

Treatment

Antitrypanosomal drug treatment is always recommended for acute, early congenital, and reactivated T. cruzi infection, and for chronic T. cruzi infection in children <18 years old. In adults with chronic infection, treatment is usually recommended.

The 2 drugs used to treat Chagas disease are benznidazole and nifurtimox. Benznidazole is approved by the US Food and Drug Administration (FDA) for use in children 2–12 years old and is commercially available. Nifurtimox is approved by the FDA for treatment of children from birth to <18 years old who weigh at least 2.5 kg. The drug was approved in August 2020 and became commercially available later that year. Side effects are common with both drugs, and tend to be more frequent and more severe with increasing age. Contact CDC (parasites@cdc.gov; 404-718-4745) for assistance with clinical management.

Prevention

To avoid Chagas disease, travelers should follow insect bite precautions (see Sec. 4, Ch. 6, Mosquitoes, Ticks & Other Arthropods) and food and water precautions (see Sec. 2, Ch. 8, Food & Water Precautions). Travelers also should avoid sleeping in adobe, mud, or thatch housing in endemic areas, and 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. Screening of pregnant people coming from endemic areas and early detection and treatment of mother-to-baby (congenital) cases also will help reduce disease burden.

CDC website: American trypanosomiasis