Alicia I. Hidron, Carlos Franco-Paredes

Infectious Agent

American Trypanosomiasis is caused by the protozoan parasite, Trypanosoma cruzi.

Mode of Transmission

Infection occurs—

• Through vector-borne transmission in endemic counties via the feces of the triatomine insect (reduviid bug), which may be inadvertently inoculated into the skin, the mucosa of eye, nose, or mouth when the insect’s bite is scratched and rubbed
• Through transfusion or organ transplantation
• From mother to infant
• By ingestion of contaminated food or drink
• Through occupational exposure in research workers

Occurrence

Approximately 7.6 million people are infected with Chagas disease, according to the most recent estimates. The disease is endemic in Mexico, Central and South America. Rare cases of Chagas disease attributed to local vector-borne transmission have been reported in the United States.

Risk for Travelers

• No cases have been documented of Chagas disease acquired during travel; the risk of acquiring Chagas disease while traveling is assumed to be extremely low.
• Travelers could be at risk for Chagas disease if staying in poor-quality housing (for example, mud walls with cracks) in endemic areas.
• Chagas disease could be acquired through blood transfusion in areas with poor screening or through the ingestion of contaminated food or drink.

Clinical Presentation

The acute phase of Chagas disease lasts up to 90 days, followed by asymptomatic chronic infection, usually undetectable by parasitologic methods. Most infected individuals never develop symptoms but remain infected throughout their lives. Those who develop acute illness will do so at least one week following exposure. A chagoma may develop, which is an area of edema and erythema at the site of infection; the classic picture is Romaña’s sign, which presents as edema of the lid and ocular tissues when the entry site was the conjunctiva. Approximately 20%–30% of infected patients will develop manifestations of chronic Chagas disease, usually involving the heart. Clinical signs include conduction system abnormalities, ventricular arrhythmias, and in late stage disease, congestive cardiomyopathy. Chronic gastrointestinal problems may ensue when Chagas causes megaesophagus or megacolon. Reactivation disease can occur in immunocompromised patients.

Diagnosis

Diagnosis requires consideration of both test results and patient exposure history. During the acute phase, parasites may be detectable in fresh preparations of buffy coat or stained peripheral blood specimens. After the acute phase, diagnosis relies on the use of at least two different serologic tests (most commonly, enzyme-linked immunosorbent assays and the immunofluorescent antibody test). Infected individuals should be evaluated for symptoms and signs of cardiac and gastrointestinal disease.

Treatment

• Consultation with an infectious disease or tropical medicine specialist for the diagnosis and treatment of Chagas disease should be advised.
• Antitrypanosomal drug treatment is always recommended for acute, early congenital, and reactivated T. cruzi infection and for chronic T. cruzi infection in children up to 18 years old. In adults, treatment is usually recommended, based on recent data suggesting that a course of antitrypanosomal treatment delays progression of cardiomyopathy and decreases mortality.
• In the United States, the only source of the antitrypanosomal drugs, benznidazole and nifurtimox, is through CDC. The drugs are not licensed in the United States and are provided only under investigational new drug protocols. Health-care providers should contact the Division of Parasitic Diseases Public Inquiries line (770-448-7775), the CDC Drug Service (404-639-3670), or, outside business hours, the CDC Emergency Operations Center (770-488-7100). CDC also provides guidance on diagnostic testing and clinical evaluation.

Preventive Measures for Travelers

• No vaccine is available.
• Preventive measures include insecticide spraying of sleeping quarters or infested houses.
• Travelers who cannot avoid camping, sleeping outdoors, or sleeping in poorly constructed houses in endemic areas should use insecticide-impregnated bed nets and tuck in the edges to provide a physical barrier to the vectors.
• Compliance with food and water precautions in endemic areas is also recommended to prevent the extremely rare occurrence of foodborne Chagas disease.
• Blood transfusion and organ transplantation should be avoided in endemic countries (see the Medical Tourism section in Chapter 2).

References

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