Epidemiological risk for Trypanosoma cruzi transmission by species of Phyllosoma complex in the occidental part of Mexico.

Domestic and peridomestic triatomine populations were collected in three rural Mexican communities of Jalisco, Nayarit and Zacatecas states. Triatoma longipennis and T. picturata (Phyllosoma complex) were the principal species unequally distributed in the villages: T. longipennis was the main species in two communities and T. picturata in the third one. Peridomestic infestation and colonization indexes were remarkably high ranging from 26.1% to 50% and from 58.3% to 85.7%, respectively. Moreover, domestic (indoor) infestation was observed in only one of the communities infested by T. longipennis. The preliminary study of temporal variation indicates increasing trend of the triatomine population and infestation rates during the dry season. Triatomine infection rates ranged from 41.2% to 60.2% and all the flagellate isolates were assigned to T. cruzi I. The majority of the dwellings were built with modern building materials and the sanitary conditions were generally good. High peridomestic infestations must be considered as a risk factor of Chagas disease transmission and further studies are needed to better understand the peridomestic conditions favoring the establishment of the triatomines. The contribution of such study to enlarger knowledge of epidemiological features of Chagas disease in Mexico is considered.