Clinical Features:
The acute phase is usually asymptomatic, but can present with manifestations that include fever, anorexia, lymphadenopathy, mild hepatosplenomegaly, and myocarditis.  Romaña's sign (unilateral palpebral and periocular swelling) may appear as a result of conjunctival contamination with the vector's feces.  A nodular lesion or furuncle, usually called chagoma, can appear at the site of inoculation.  Most acute cases resolve over a period of a few weeks or months into an asymptomatic chronic form of the disease.  The symptomatic chronic form may not occur for years or even decades after initial infection.  Its manifestations include cardiomyopathy (the most serious manifestation); pathologies of the digestive tract such as megaesophagus and megacolon; and weight loss.  Chronic Chagas disease and its complications can be fatal.

Laboratory Diagnosis:
Demonstration of the causal agent is the diagnostic procedure in acute Chagas disease.  It almost always yields positive results, and can be achieved by:

• Microscopic examination: a) of fresh anticoagulated blood, or its buffy coat, for motile parasites; and b) of thin and thick blood smears stained with Giemsa, for visualization of parasites.
• Isolation of the agent: a) inoculation in culture with specialized media (e.g. NNN, LIT); b) inoculation into mice; and c) xenodiagnosis, where uninfected triatomine bugs are fed on the patient's blood, and their gut contents examined for parasites 4 weeks later.

Note: In certain circumstances, investigational molecular diagnostic tools, such as PCR, may be useful.

Diagnostic Findings

• Microscopy
• Antibody detection

Treatment:
Medication for Chagas disease is usually effective when given during the acute phase of infection and may be indicated for patients in the chronic phase as well.  The drugs of choice are benznidazole or nifurtimox (under an Investigational New Drug protocol from the CDC Drug Service).  For additional information, see the recommendations on CDC's Division of Parasitic Diseases Chagas Disease Web site.  For additional information, see the recommendations in The Medical Letter (Drugs for Parasitic Infections).