[Natural Trypanosoma cruzi infection of Triatominae bugs associated with human habitations in Mexico ]. / Infección natural de chinches Triatominae con Trypanosoma cruzi asociadas a la vivienda humana en México.

OBJECTIVE: To estimate the prevalence of infection with Trypanosoma cruzi in Triatominae species frequently found in and around Mexican dwellings, and to assess the frequency of Triatominae in towns by state. MATERIAL AND METHODS: Between January 1993 and December 1999, 5,399 Triatominae bugs from 14 states of Mexico, were received in the Department of Entomology of the Institute for Epidemiologic Diagnosis and Referral (InDRE), for taxonomic determination and parasitoscopical search of Trypanosoma cruzi. Results obtained between 1993 and 1999 were analyzed globally. RESULTS: From 13 bug species associated with human dwellings, nine were naturally infected with T. cruzi. The highest percentage of infection occurred in Triatoma pallidipennis, T. picturata, Rhodnius prolixus and T. longipennis. Nayarit, Morelos, and Michoacán were the states with the highest percentage of infected bugs. The species T. dimidiata, T. gerstaeckeri, T. longipennis, T. mexicana and T. pallidipennis were first state records and Pastrongylus rufotuberculatus was a first local record. CONCLUSIONS: These findings stress the importance of studying the biology of Triatominae and the need for permanent surveillance, to allow for up-to-date distribution records of Triatominae species in and around human dwellings, those adapting to human dwellings, and frequencies of those naturally infected by T. cruzi.

First record in America of Aedes albopictus naturally infected with dengue virus during the 1995 outbreak at Reynosa, Mexico.

Mosquito collections were conducted during a dengue outbreak in Reynosa, Tamaulipas, Mexico, July-December 1995. A total of 6694 adult mosquitoes (four genera and nine species) were captured, of which 2986 (78.3% females and 21.7% males) were Aedes albopictus and 2339 (39.7% females and 60.3% males) were Ae.aegypti. These two species comprised 84.2% of the total collection. Specimens were grouped into pools, nearly 50% of them processed for detection of virus by cythopathic effect in C6-36 and VERO cell cultures and by haemagglutination test. Five pools gave positive haemagglutination reactions and were examined by immunofluorescence using monoclonal antibodies to flavivirus and to dengue virus. One pool of ten Ae.albopictus males was positive for dengue virus: serotypes 2 and 3 were identified by serotype-specific monoclonal antibodies and confirmed by RT-PCR. This is the first report of Ae.albopictus naturally infected with dengue virus in America. Also, it is the very first time Ae.albopictus males have been found infected with dengue virus in the wild.

Aedes albopictus in Mexico.

Data relating to the discovery and identification of the Asian tiger mosquito, Aedes albopictus, in Coahuila State, Mexico, are presented. Infestations are reported for Piedras Negras and Ciudad Acuña. Samples from a third community were negative for Ae. albopictus.