Time-specific ecological niche modeling predicts spatial dynamics of vector insects and human dengue cases.

Numerous human diseases-malaria, dengue, yellow fever and leishmaniasis, to name a few-are transmitted by insect vectors with brief life cycles and biting activity that varies in both space and time. Although the general geographic distributions of these epidemiologically important species are known, the spatiotemporal variation in their emergence and activity remains poorly understood. We used ecological niche modeling via a genetic algorithm to produce time-specific predictive models of monthly distributions of Aedes aegypti in Mexico in 1995. Significant predictions of monthly mosquito activity and distributions indicate that predicting spatiotemporal dynamics of disease vector species is feasible; significant coincidence with human cases of dengue indicate that these dynamics probably translate directly into transmission of dengue virus to humans. This approach provides new potential for optimizing use of resources for disease prevention and remediation via automated forecasting of disease transmission risk.

Infectious diseases in Mexico. A survey from 1995-2000.

Data obtained at a central laboratory for emerging, re-emerging, and other infectious diseases in Mexico from 1995-2000 are presented. An outstanding increase of DEN-3 circulation was identified. Aedes aegypti, the dengue vector, is widely distributed. Leptospirosis has become the most important differential diagnosis for dengue. Identification of rabies virus variants allowed cataloging of new transmitters of rabies. Rotavirus showed a clear seasonal distribution, while different proportions of pathogenic classes of Escherichia coli under endemic and outbreak conditions were seen. Serotypes of several bacteria are reported as well as the sources of isolation and frequency of Shigella, Salmonella, and Vibrio cholerae. Rise and disappearance of cholera could be followed along the past decade. Influenza strains were identified, as were several pathogens causing sexually transmitted infections. Laboratory support was important for surveillance after Hurricane Mitch. Multidrug-resistant strains of Mycobacterium tuberculosis are emerging and primary resistance is very high. It is now mandatory to search for antibodies to Trypanosoma cruzi in blood banks. Triatoma barberi, a peridomestic bug, is the main vector of Chagas disease. Localized cutaneous leishmaniosis increased in regions having a guerrilla element in Chiapas. Modern immunodiagnostic techniques are used for control studies of cysticercosis and similar techniques were recently standardized for Trichinella spiralis detection. Low iodine values in children's urine were found in several Mexican states; therefore, use of iodized salt should be encouraged.

Infección natural de chinches Triatominae con Trypanosoma cruzi asociadas a la vivienda humana en México / Natural infection of Triatominae bugs in Mexican dwellings

Objetivo. Informar el porcentaje de infección natural de las especies de triatóminos que habitan con mayor frecuencia el medio doméstico y peridoméstico en México, así como dar a conocer las localidades de colecta por estado. Material y métodos. Se recibieron muestras de chinches Triatominae en el Departamento de Entomología del Instituto de Diagnóstico y Referencia Epidemiológicos, para su determinación taxonómica y la búsqueda parasitoscópica de Trypanosoma cruzi, provenientes de 14 estados del país, de enero de 1993 a diciembre de 1999. Se analizaron en conjunto los resultados obtenidos en esos años. Resultados. De una muestra de 5 399 ejemplares, fueron 13 las especies de triatóminos asociadas a las viviendas. El porcentaje de infección natural tuvo una amplia variación entre las especies. De las estudiadas, nueve se encontraron con infección natural; el mayor porcentaje de infección corresponde a Triatoma pallidipennis, T. picturata, Rhodnius prolixus y T. longipennis. Los estados con mayor porcentaje de infección fueron Nayarit, Morelos y Michoacán. Se presentaron nuevos registros estatales de Triatoma dimidiata, T. gerstaeckeri, T. longipennis, T. mexicana y T. pallidipennis y uno local de Pastrongylus rufotuberculatus. Además, se informa por primera vez la infección natural en algunas de ellas. Conclusiones. Se debe poner mayor énfasis en el estudio de la biología y aspectos bionómicos de los triatóminos y realizar una vigilancia permanente para tener los registros de distribución actualizados, así como para conocer los índices de infección natural por T. cruzi, de las especies domiciliarias, peridomiciliarias y de las que están en proceso de adaptación a la vivienda humana.