What are the current treatments for Chagas disease and their limitations?
The disease has two clinical phases, the acute phase (fatal for 2-8% of children), which is often asymptomatic or poorly symptomatic and unrecognized, and the chronic phase, which can be divided into two stages:
- The chronic, asymptomatic (or indeterminate) stage, during which patients can transmit the parasite to others (mostly through blood, congenital transmission, or occasionally organ transplant) and which may last decades after infection.
- The chronic, symptomatic stage, developing later in up to 30% of infected patients. Chagas disease causes abnormal dilation of the large intestine (megacolon), is the leading cause of infectious heart disease (cardiomyopathy) in the world, and the leading cause of death from a parasitic disease in Latin America.
Current treatments, benznidazole and nifurtimox, are effective against the acute phase of infection, and while there is increasing evidence of their efficacy in the chronic indeterminate phase of the disease, broad use of these drugs has been limited due to lack of guidelines and policies supporting implementation. Drawbacks include long treatment periods (60-90 days), dose-dependent toxicity, and a high drop-out rate of patients due to side-effects. There is currently no approved treatment for the chronic form of the disease with target organ involvement (chronic symptomatic stage).