Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 35-02: American Trypanosomiasis (Chagas Disease) + Key Features Download Section PDF Listen +++ +++ Essentials of Diagnosis +++ Acute stage ++ Inflammatory lesion at inoculation site Fever Hepatosplenomegaly Lymphadenopathy Myocarditis Parasites in blood is diagnostic +++ Chronic stage ++ Heart failure, cardiac arrhythmias Thromboembolism Megaesophagus Megacolon Serologic tests are usually diagnostic +++ General Considerations ++ Caused by Trypanosoma cruzi, a protozoan parasite Parasite infects wild animals and, to a lesser extent, humans from southern South America to southern United States T cruzi has a predilection for myocardium, smooth muscle, and CNS glial cells In many countries in South America, Chagas disease is the most important cause of heart disease Infection occurs when parasite penetrates skin through bite wound, mucous membranes, or conjunctiva As disease progresses over decades, multiplication of parasite causes Cellular destruction Inflammation Fibrosis +++ Demographics ++ An estimated 8–10 million people are infected, mostly in rural areas, with the highest national prevalence in Bolivia, Argentina, Paraguay, Ecuador, El Salvador, and Guatemala In endemic countries, incidence has decreased to about 40,000 new infections and 12,500 deaths per year In the United States, only a few instances of local transmission have been reported + Clinical Findings Download Section PDF Listen +++ +++ Symptoms and Signs ++ Up to 70% of persons remain asymptomatic +++ Acute stage ++ Seen principally in children Lasts 1–2 months The earliest findings are at the inoculation site In the eye—Romaña sign (unilateral edema, conjunctivitis, lymphadenopathy) or In the skin—a chagoma (swelling with local lymphadenopathy) Subsequent findings include Fever Malaise, headache Mild hepatosplenomegaly Generalized lymphadenopathy Acute myocarditis and meningoencephalitis are rare but can be fatal +++ Latent stage (indeterminate phase) ++ This asymptomatic stage may last for life, but symptomatic disease develops in 10–30% of infected individuals, commonly many years after infection +++ Chronic stage ++ Generally manifests as abnormalities in cardiac and smooth muscle Cardiac disease includes Arrhythmias Heart failure Embolic disease Smooth muscle abnormalities lead to megaesophagus and megacolon with Dysphagia Regurgitation Aspiration Constipation Abdominal pain These findings can be complicated by superinfections Latent Chagas disease may reactivate in immunosuppressed patients; findings include brain abscess and meningoencephalitis +++ Differential Diagnosis ++ Acute stage: malaria, rheumatic fever, African trypanosomiasis Myocarditis due to other causes, eg, coxsackievirus, drugs Coronary artery disease Toxic megacolon due to inflammatory bowel disease or Clostridioides difficile–associated colitis + Diagnosis Download Section PDF Listen +++ +++ Laboratory Tests +++ Acute stage ++ Evaluation of fresh blood or buffy coats may show motile trypanosomes Fixed preparations may show Giemsa-stained parasites Concentration methods increase diagnostic yields Trypanosomes may be identified in lymph nodes, bone marrow, or pericardial or spinal fluid Molecular tests are highly sensitive, and can be used to detect parasites in organ transplant recipients or after accidental exposure When initial tests are unrevealing in a suspicious case, xenodiagnosis, using laboratory vectors, laboratory culture, or animal inoculation may provide a diagnosis, but these methods are expensive and slow +++ Chronic stage ++ Diagnosed serologically Sensitivity and specificity not ideal Confirmatory assays are advised after initial positive test Diagnosis of chronic disease with polymerase chain reaction (PCR) remains suboptimal + Treatment Download Section PDF Listen +++ +++ Medications ++ Treatment is inadequate because the two drugs used, benznidazole and nifurtimox, often cause severe side effects, must be used for a long period, and are ineffective in chronic infection Nevertheless, all T cruzi-infected patients should be treated regardless of clinical status or time since infection In particular, treatment is recommended for acute, congenital, and reactivated infections and for children and young adults with chronic disease Benznidazole 5 mg/kg/day orally in divided doses for 60 days Side effects include granulocytopenia, rash, and peripheral neuropathy Nifurtimox 8–10 mg/kg orally in four divided doses after meals for 90–120 days Side effects include gastrointestinal (anorexia, vomiting) and neurologic symptoms (headaches, ataxia, insomnia, seizures), which appear to be reversible and to lessen with dosage reduction In the United States, nifurtimox is available only from the CDC Drug Service, Centers for Disease Control and Prevention, Atlanta, GA 30333; telephone: 404-639-3670 Patients with chronic disease may also benefit from Antiarrhythmic therapy Standard therapy for heart failure Conservative and surgical management of megaesophagus and megacolon + Outcome Download Section PDF Listen +++ +++ Prognosis ++ In acute and congenital infections, nifurtimox and benznidazole reduce duration and severity of infection, but cure is achieved in only about 70% of patients In the chronic phase, although parasitemia may disappear in up to 70% of patients, treatment does not alter progression of disease +++ Prevention ++ In South America, reductions in new infections has been achieved by initiation of a major eradication program based on Improved housing Use of residual pyrethroid insecticides and pyrethroid-impregnated bed curtains Screening of blood donors In endemic areas, blood should not be used for transfusion unless at least two serologic tests are negative + References Download Section PDF Listen +++ + +Bern C. Chagas' disease. N Engl J Med. 2015 Jul 30;373(5):456–66. [PubMed: 26222561] + +Lozano D et al. Use of rapid diagnostic tests (RDTs) for conclusive diagnosis of chronic Chagas disease—field implementation in the Bolivian Chaco region. PLoS Negl Trop Dis. 2019 Dec 19;13(12):e0007877. [PubMed: 31856247] + +Morillo CA et al; BENEFIT Investigators. Randomized trial of benznidazole for chronic Chagas' cardiomyopathy. N Engl J Med. 2015 Oct;373(14):1295–306. [PubMed: 26323937] + +Pérez-Molina JA et al. Chagas disease. Lancet. 2018 Jan 6;391(10115):82–94. [PubMed: 28673423] + +Schijman AG. Molecular diagnosis of Trypanosoma cruzi. Acta Trop. 2018 Aug;184:59–66. [PubMed: 29476727] + +Whitman JD et al. Chagas disease serological test performance in U.S. blood donor specimens. J Clin Microbiol. 2019 Nov 22;57(12):e01217–19. [PubMed: 31511333]