Peridomicilary habitat and risk factors for Triatoma infestation in a rural community of the Mexican occident.

An examination of peridomestic area organization and triatomine collection in an endemic village for Chagas disease (Jalisco State) identified the habitat of Triatoma longipennis (dominant species) and the risk factors of peridomestic infestation. In 100 visited peridomestic areas, 369 structures (permanent, temporary, and natural) were submitted to active manual research of triatomines. Storage shelters had a higher infestation of T. longipennis than piles of brick and tile; baked clay material had higher degrees of infestation than others. The secondary species Triatoma barberi shares a wide range of peridomicilary habitats with T. longipennis. Peridomestic area infestation risks (evaluated with multivariate logistic regression analysis) are number of closed storage shelters, number of brick and tile piles, number of houses per peridomestic areas, and distance of peridomicile from natural environment. Because both species present great adaptability to different artificial habitats, strategies of control must involved improving the overall management of peridomestic areas to prevent stable colonization.

Peridomestic colonization of Triatoma longipennis (Hemiptera, Reduviidae) and Triatoma barberi (Hemiptera, Reduviidae) in a rural community with active transmission of Trypanosoma cruzi in jalisco state, Mexico.

Infestation of peridomiciles is likely a major risk factor for Chagas disease transmission in Jalisco state, Mexico. An entomological and serological survey of a typical village was conducted between July and September 2003. The peridomestic areas of 100 dwellings were visited and triatomines were searched manually in 369 potential sites. A total of 1821 Triatoma longipennis (93.2%) or Triatoma barberi was captured. Both species frequently occurred in sympatry. The infestation index was 60% for T. longipennis and 16% for T. barberi. T. longipennis occurred throughout the village. Colonization indices were high for T. longipennis (93%) and T. barberi (75%), suggesting that both species have adapted to peridomestic habitats. The bug population size was larger for T. longipennis than for T. barberi. Five very large colonies of T. longipennis were recorded whereas only 1 or 2 bugs were observed in 38% of the positive sites, which suggests intense dispersal activity. Both species exhibited high infection prevalence with Trypanosoma cruzi (46%). Only T. cruzi lineage I was detected. Human seroprevalence was 1.8%. This study serves as an entomological overview of peridomiciliar triatomine colonization in a Mexican village and highlights the current risk of Chagas disease transmission.

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.

Identification in triatomine vectors of feeding sources and Trypanosoma cruzi variants by heteroduplex assay and a multiplex miniexon polymerase chain reaction.

Feeding sources of triatomine vectors (Triatoma longipennis) collected in peridomiciles in Mexico were identified by a heteroduplex assay developed with triatomine blood meals. Trypanosoma cruzi parasites were also characterized in the same blood meal samples by multiplex-polymerase chain reaction assay of mini-exon gene inter-genic regions. The main blood meal source was from rats, but the bugs were able to feed on a wide variety of hosts, and human blood meals were identified. Trypanosoma cruzi was the only flagellate species identified in the blood meals. All populations belong to the T. cruzi I lineage, a result that is consistent with the previously assumed predominance of this lineage in Mexico. This combination of blood meal and T. cruzi lineage identification provides a powerful tool for understanding T. cruzi transmission cycles.

Seguimiento serológico de infección por Trypanosoma cruzi en individuos estudiados de 50 municipios del Estado de Jalisco, México de 1987 a 1994 / Serological follow-up of Trypanosoma cruzi infection from 1987 to 1994 in 50 counties of the State of Jalisco, Mexico

La Universidad de Guadalajara decidio realizar en 1987 un estudio seroepidemiologico para conocer la prevalencia de la infeccion por Trypanosoma cruzi en los 124 municipios del Estado de Jalisco, Mexico, en el cual se obtuvieron tasas de 21,6 por 100 habitantes. De diciembre de 1993 a junio de 1994 se realizo un seguimiento de algunos de esos individuos, estudiandose sólo 2669 de ellos, de 50 municipios de ßreas rurales del estado. Las causas de no encuesta de los faltantes fueron diversas, estando entre las mas importantes la emigracion (27,6 )y la renuencia (14,8). Encontramos a 476 positives (17,8 por cento) y 2193 negatives (82,2 por cento). Este segundo estudio nos permitio detectar 80 infectados nuevos (2,9 por cento) lo que representa una tasa de incidencia de 30 por 1000 habitantes. Sin embargo, encontramos una seroconversion en los individuos estudiados, ya que de 1007 individuos que estaban positivos en 1987, 943 de ellos continuan asi, mientras, que 64 individuos se negativizaron (2,3 por cento), no siendo esto imputable a fallas de laboratorio, la prevalencia de positividad detectada en ambos estudios fue casi identica 18, 1 y 17,8 por cento respectivamente, por lo que nosotros pensamos que las condiciones en que viven los individuos de las localidades rurales del Estado de Jalisco favorecen a que las infecciones continuen