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Chagas disease is a zoonosis caused by the parasite Trypanosoma cruzi; its cycle originally involved the insect vectors (Triatominae) and wild mammals. When the vectors colonized human dwellings after the degradation of their natural habitats, they got in contact with humans and started a "domestic" cycle of T. cruzi transmission.

The control of the vectorial transmision of Chagas disease (with a national prevalence of 8%) is a Public Health priority in Guatemala. Since year 2000 a massive control campaign is being carried out in nine provinces of the country.

Two vector species are the major targets of chemical control: Rhodnius prolixus and Triatoma dimidiata. R. prolixus is suspected to be an artificially introduced species in Central America (Dujardin et al 1998), and its eradication from human dwellings is expected after insecticide sprayings.

On the contrary, T. dimidiata is a native species that colonizes the intra- and peri- domestic environments, and is also present in various sylvatic habitats (Zeledón 1981). After the disappearance of the effects of insecticides inside houses, a reinfestation by T. dimidiata is expected, with bugs probably coming from peridomestic or sylvatic environments. Reinfestation has already been observed in southeastern Guatemala (Ministry of Health personal communications).

Experts coincide when say that it is not possible to eradicate T. dimidiata, and then is necessary to learn how to live with it, but reducing the human-vector contact.

We propose the application of an ecosystem approach to confront this problematic. We will study the complexity of an agroecosystem in an eastern province of Guatemala to develop a sustainable solution. First, the socio-economic and ecologic aspects of the ecosystem should be characterized. To understand the reinfestation process is necessary to study the interactions between people, environment and the vector, at three levels: intradomestic, peridomestic and sylvatic. It is important to determine if the reinfestation of houses is due to inmigration of insects or to its survival after the sprayings.

Based in this knowledge it will be possible to develop solutions involving: (a) empowering of the population with information for decision making processes; (b) involvement of population in actions oriented to avoid the vectors colonization on the intradomestic and peridomestic environments; (c) a better management of the agroecosystem (the sylvatic environment) to prevent the disappearance of the natural ecotopes of the vector and maintain the disease as a "sylvatic" zoonosis.

Presenter: Dulce Maria BUSTAMANTE ZAMORA*

Click below to view the Power Point presentation discussed at the International Forum on Ecosystem Approaches to Human Health, Montreal, May 18-23, 2003.

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