Chagas disease is confined to South and Central America. Chagas disease is usually spread by the feces of reduviid bugs, insects that live in cracks and holes of poorly constructed houses and outbuildings in South and Central America. The bugs become infected after biting an infected animal or person. Once infected, the bugs pass Trypanosoma parasites in their feces. People get infected when they unknowingly rub bug feces into their eyes or mouth or into a skin wound or bite.
People can also become infected by eating uncooked food contaminated with infected bug feces.
Chagas disease can be transmitted by contaminated blood transfusions or by organ transplants. Infected women can pass the infection to their babies during pregnancy, at delivery, or while breastfeeding. Some people can be infected and never develop symptoms. For those who do, Chagas disease has three stages, each with different symptoms. The most recognized acute symptom is swelling of the eye on one side of the face, usually at the bite wound or where feces were rubbed into the eye.