Chagas disease: Importance of rats as reservoir hosts of Trypanosoma cruzi (Chagas, 1909) in western Mexico

In Mexico, the role of most species of mammals involved in the transmission cycle of Trypanosoma cruzi Chagas, 1909 is poorly known. It was carried out a study to investigate the importance of rats as reservoir of T. cruzi in western Mexico, an area with important risk of transmission of T. cruzi to human. Thirty-eight human dwellings were searched on two representative towns of western Mexico along twelve months for collection of rats and triatomines. Study rats (Rattus norvegicus) Berkenhout, 1769 and triatomines (Meccus phyllosomus longipennis) (Usinger, 1939) were collected inside and outside human dwellings. Most rats (68.6%, n = 312) and triatomines (68.7%, n = 217) were collected along months of the hot season. Most rats (59.3%) were collected in peridomiciliary areas. From 312 examined rats, 71 (22.7%) were positive for T. cruzi on examination by Indirect Hemagglutination, which was confirmed by xenodiagnosis. From the 217 examined triatomines, 169 (77.9%) were infected by T. cruzi. The presence of infected rats and triatomines was highly related since on every studied human dwelling where infected triatomines were collected, infected rats were also found. Rats seem to constitute an important domiciliary and peridomiciliary reservoir for T. cruzi, furthering the risk of infection for human beings.