The hemipteran triatomine bugs are vectors of Trypanosoma cruzi, the causative agent of Chagas disease in the western hemisphere in South and Central America.

American trypanosomiasis or Chagas disease

American trypanosomiasis, or Chagas disease, is caused by the protozoan parasite, Trypanosoma cruzi. The infection is usually transmitted via the faeces of blood-sucking reduviid bugs which belong to the Triatominae subfamily (kissing bugs). The infection is found in small mammals that serve as reservoir hosts in a sylvatic cycle and human disease results from the colonization of the human habitat by some vector species in a domestic cycle.

Vectorial transmission (via the faeces) is responsible for 80% of human infections. The entry of metacyclic trypomastigotes via the mucosal route (oral or ocular) is easy. Direct skin penetration is more difficult, and generally, the para– site enters through the site where the bug has taken a blood-meal through the lesions which result from scratching a bite. In South and Central America transmission by transfusion of infected blood (containing trypomastigotes) is responsible for 5–20% of the human cases of Chagas disease, mainly in urban centres.

The disease is found only in the American hemisphere. It is endemic in 21 countries; as a result of major control campaigns there is a decreasing trend in its prevalence and eradication of the disease has been achieved in Chile and Uruguay.