Chagas disease, which now affects at least 300,000 U.S. residents, is widely scattered across more than 40 states and growing in prevalence in traditionally nonendemic areas, according to a scientific statement from the American Heart Association.
Traditionally regarded as a tropical disease found only in Central and South America, Chagas disease results from the protozoan Trypanosoma cruzi and is an important cause of heart failure, stroke, arrhythmia, and sudden death, the statement said.
An unknown number of people have been infected by local transmission in the U.S., and “recent evidence suggests that locally acquired T. cruzi infection can result in cardiomyopathy, but existing data are not adequate to assess the magnitude of this problem or to map the areas of highest risk,” said the scientific statement, which was published Aug. 20 by Circulation.
Clinicians and health systems outside of Latin America need to be equipped to recognize, diagnose, and treat Chagas disease and to prevent further disease transmission, reported the statement. The CDC has targeted Chagas disease as one of five neglected parasitic infections in the United States, it noted.
From 60% to 70% of infected individuals remain asymptomatic, the statement said. Outcomes vary from conduction defects and mild segmental wall motion abnormalities to severe symptoms of heart failure, thromboembolic phenomena, and life-threatening ventricular arrhythmias.
The acute phase of Chagas disease typically lasts eight to 12 weeks, but it is often undiagnosed because most patients are asymptomatic or have mild, nonspecific symptoms such as fever, malaise, and splenomegaly. After the acute phase of infection, most patients pass into a chronic indeterminate form defined by positive anti-T. cruzi serology, no physical signs or symptoms of disease, a normal EKG, and normal radiographs of the chest, esophagus, and colon.
Indeterminate Chagas disease will progress to clinically manifest disease, usually dilated cardiomyopathy, at a rate of 1.85% to 7% annually, the scientific statement said. The prognosis for patients with indeterminate Chagas disease is good, with most surviving without major complications for at least five to 10 years and carrying the same risk of death as the general population, as long as EKGs remain normal, the statement said.
Chronic Chagas heart disease develops after several decades of the indeterminate form, the statement said. Chagas cardiomyopathy is the most important clinical manifestation of Chagas disease, resulting in most morbidity and mortality. Most studies have found sudden death to be the most common overall cause of death (55% to 60%), followed by heart failure (25% to 30%) and embolic events (10% to 15%).
“Detection and diagnosis of chronic Chagas heart disease in traditionally nonendemic environments require a high index of suspicion,” the statement advised. A 12-lead EKG may detect occult chronic Chagas disease in asymptomatic patients. In symptomatic patients, the most common presenting features in symptomatic patients include those related to heart failure, bradyarrhythmias or tachyarrhythmias, thromboembolic events, and microvascular abnormalities, the statement said: “When these signs and symptoms are present without a clear diagnostic confirmation, history of risk factors for T cruzi infection should be sought, and specific serological tests must be used to confirm or rule out the diagnosis of Chagas disease.”
Benznidazole and nifurtimox are the only drugs that have proven efficacy against Chagas disease. The former is the first-line treatment because it has better tolerance, is more widely available, and has more published data on its efficacy. It became available in the U.S. on May 14, but prescriptions require submission of a completed Fast Access order form, the statement said.