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Evaluation of the reinfestation danger of T.infestans from its sylvestrian fours into the target area of the domestic eradication project of the "Cono Sur" countries

Objective



In November 1991, a vector eradication programme covering the whole territory of Triatoma-infestans (T.i) was officially decided by the "Cono Sur" region. Until now, this major vector of Chagas disease did not exhibit any resistance to the presently used pyrethroid insecticides and, due to its quite long generation time, probability of such an event is weak. Vectorial transmission of Trypanosoma-cruzi in "Cono Sur" is particularly vulnerable to domiciliar insecticide application because T.i is almost exclusively domesctic. As far, the unique case of wild living T.i was described in Bolivia (Dujardin et al., 1987 ; Schofield, 1988). Selvatic specimens of Ti in the Cochabamba valley were found infected by T.cruzi zymodemes also isolated from domestic cycle, and did not present any evidence of geographical separation versus the nearest domestic T.i. Since at this time there was no scheduled vector control programme, local-dispersion ability of wild insects was not further investigated, and geographic extension of this wild focus remained completely unknow. In order to reduce risks of reinfestation from wild foci following the near eradication of domestic T.i in Bolivia, more data are urgently needed about the connections between wild and domestic T.i of Cochabamba, as well as about geographic location and taxonomic status of other suspected wild foci near Sucre. Our project should contribute to the correct delimitation of the geographic area where selvatic T.i occur. Within the recognised foci, specific investigations would follow, using "external" ("sentinel henhouses") and "internal" markers (genetic characterisation of the isolated parasite stocks, isozymes and chromosome C-banding of insects), in order to explore the relationships with parasite domestic cycle, the dispersion behaviour of wild insects and their tendency to invade the nearest domestic structures. on the other hand, seasonal captures and laboratory rearing would allow a comprehensive study of wild populations ecology and dynamics..

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Institut Français de Recherche Scientifique pour le Développement en Coopération (ORSTOM)
Address
911 Avenue Agropolis
34032 Montpellier
France

Participants (2)

Natural History Museum
United Kingdom
Address
Cromwell Road
SW7 5BD London
UNIVERSIDAD MAYOR DE SAN SIMON
Bolivia
Address
Avenida Aniceto Arce 0371
Cochabamba