Chagas disease (also called American trypanosomiasis) is a Mammalian disease occurring only in the Americas.

It is caused by the protozoan Trypanosoma cruzi, one of the kinetoplastid flagellates, transmitted to humans by triatomine insects known in the different countries as assassin bug, vinchuca, kissing bug, chipo etc. usually Triatoma protracta.

The human disease occurs in two stages: the acute stage shortly after the infection and is usually mild fever and swelling around the bite area, 10-30 % of those bitten develop the chronic stage which appears after several years. The disease affects the nervous system and heart. Chronic infections result in various neurological disorders, including dementia, damage to the heart muscle, and sometimes dilation of the digestive tract (megacolon and megaesophagus). Left untreated, Chagas disease can be fatal.

The disease was named after the Brazilian physician Carlos Chagas who first described it in 1910 but the disease was not seen as a major problem in humans until the 1960s. Chagas disease currently affects 16-18 million people, killing around 20,000 annually and with some 100 million at risk of acquiring the disease.

The disease causing agent, Trypanosoma cruzi, is closely related to that of African sleeping sickness, although the assassin bug vector is not closely related to the tsetse fly, which carries African sleeping sickness.

It has been hypothesized that Charles Darwin might have suffered from this disease as a result of a bite of the so-called Great Black Bug of the Pampas (Triatoma).

See also: achalasia