Diagnosis and Treatment
Chagas disease has two successive phases: an acute phase and a chronic phase.
Most acute phases are asymptomatic or have non-specific symptoms.
During the chronic phase patients may also be symptom-free but some may progress to clinical forms of the disease (cardiac, digestive and/or neurological), which can be life threatening if left undiagnosed and untreated.
During the acute phase or during reactivation because of immunosuppression (which can be caused by old age, radiation, chemotherapy or AIDS), diagnosis is made by direct detection of the parasite circulating in the bloodstream.
During the chronic phase, when the parasite is hidden in target tissues, diagnosis is made via the detection of antibodies against T. cruzi (serological techniques).
Treatment is urgently indicated for anyone during the acute phase and for those in whom the infection has been reactivated (immunosuppression). In these situations, treatment is almost 100% effective, and the disease can be completely cured.
However, efficacy decreases as the duration of the infection lengthens. Moreover, infants are less likely to have adverse events from treatment but this risk increases with age.
Treatment is also indicated for infants with congenital infection and for patients during the early chronic phase.
Adults, especially those with the indeterminate form of the disease, should be offered treatment, but its potential benefits in preventing or delaying the development of Chagas disease should be weighed against the long duration and frequent adverse events.
During the late chronic phase, when cardiac or digestive manifestations may occur, additional lifelong medical treatment and surgery are usually indicated.
As described earlier, the two medicines used for treatment are benznidazole, often the first-line treatment in most countries; and, nifurtimox. The main contraindications to treatment are pregnancy and kidney or liver failure. Nifurtimox is contraindicated in patients with a history of psychiatric or neurological disorders.