Phases and forms of Chagas disease

The natural history of Chagas disease is divided into two phases, acute and chronic. The acute phase lasts approximately 8 weeks, and usually causes mild or no symptoms.

Patients with chronic Chagas disease have lifelong infection in absence of treatment. Spontaneous cure is extremely rare.

These patients can be categorized as having one of two forms:

• Indeterminate form, in which the patient has no signs or symptoms or
• Determinate forms, with clinical manifestations of Chagas disease

Most chronically infected persons remain asymptomatic for life. However, approximately 20% to 30% of T. cruzi-infected persons progress to clinical manifestations characteristic of Chagas disease (determinate forms) over the course of their lifetimes.

The most common clinical manifestation is heart disease, often referred to as Chagas cardiomyopathy.

A time line of Chagas disease showing that Acute Chagas disease occurs immediately after infection and may last for a few months; during the acute phase, parasites may be found in the circulating blood as soon as 1 to 2 weeks after infection. Following the acute phase, most infected people enter into a prolonged asymptomatic form of disease (called "chronic indeterminate") during which few or no parasites are found in the blood. Many people may remain asymptomatic for life. However, approximately 20% to 30% of infected people will develop clinical disease over the course of their lives.