infectious diseases
Chagas Disease
Key Points
Chagas disease is caused byTrypanosoma cruzi, which is transmitted by Triatominae (reduviid, kissing, or assassin) bugs. Infection is endemic in South and Central America and Mexico; an estimated 8 million people worldwide, including an estimated 300,000 people in the US (primarily immigrants), are infected. Acute infection is followed by a chronic indeterminate period, which may remain asymptomatic, but in 20 to 30% of patients, it progresses to chronic disease, which particularly affects the heart and/or gastrointestinal (GI) tract. Diagnose acute Chagas using light microscopy of blood smears (thin or thick) or a tissue sample or PCR-based assays. Diagnose chronicT. cruziinfection by screening enzyme-linked immunosorbent blood assay (ELISA) with confirmatory radioimmunoprecipitation assay (RIPA) or other assay for antibodies. Use PCR-based tests to evaluate cases potentially transmitted transplacentally or via transfusion, transplantation, or laboratory exposure. To detect chronic Chagas disease, do echocardiography if patients have symptoms suggesting heart disease or potential cardiac abnormalities on a chest x-ray, ECG, or rhythm strip; do GI contrast studies or endoscopy if they have dysphagia or other GI symptoms. The antiparasitic drugsbenznidazoleornifurtimoxare used to treat acute, congenital, or reactivated Chagas disease. They are also used for chronic infection in children up to age 18 years. They are strongly recommended for adults 18 to 50 years who do not have advanced cardiac or evidence of GI disease. For patients > 50 years with chronic infection, treatment is individualized based on balance of risks and benefits. Antiparasitic drugs are not effective in patients with advanced Chagas cardiac or gastrointestinal disease, but supportive measures (eg, treatment of heart failure, pacemakers for heart block, antiarrhythmic drugs, cardiac transplantation, esophageal dilation, botulinum toxin injection into the lower esophageal sphincter, GI tract surgery) are often helpful. 