A disease caused by the parasite Trypanosoma cruzi (a type of protozoa). Chagas disease is most commonly transmitted when people come into contact with the feces of an infected riduviid bug, a blood-sucking insect that feeds on humans and animals. In the earliest stage of infection, Chagas disease usually has few signs or symptoms. However, if untreated, the disease becomes a lifelong infection. In people with HIV, reactivation of chronic Chagas disease infection can cause inflammation of the brain and meninges (meningoencephalitis).