Biogeography of Triatominae (Hemiptera: Reduviidae) in Ecuador: Implications for the Design of Control Strategies
Fernando Abad-Franch/*, Aura Paucar C*/++, Carlos Carpio C*, César A Cuba Cuba**, H Marcelo Aguilar V*/***, Michael A Miles/+
Pathogen Molecular Biology and Biochemistry Unit, Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel St., London WC1E 7HT, UK *Unidad de Medicina Tropical, Instituto 'Juan César García', Quito, Ecuador **Unidade de Parasitologia Médica-Patologia, Faculdade de Medicina, Universidade de Brasília, DF, Brasil ***Instituto Nacional de Higiene y Medicina Tropical `Leopoldo Izquieta Pérez', Quito, Ecuador
Chagas disease control strategies strongly depend on the triatomine vector species involved in Trypanosoma cruzi transmission within each area. Here we report the results of the identification of specimens belonging to various species of Triatominae captured in Ecuador (15 species from 17 provinces) and deposited in the entomological collections of the Catholic University of Ecuador (Quito), Instituto Oswaldo Cruz (Brazil), the Natural History Museum London (UK), the London School of Hygiene and Tropical Medicine (UK), the National Institute of Hygiene (Quito), and the Vozandes Hospital (Quito). A critical review of published information and new field records are presented. We analysed these data in relation to the life zones where triatomines occur (11 life zones, excluding those over 2,200 m altitude), and provide biogeographical maps for each species. These records are discussed in terms of epidemiological significance and design of control strategies. Findings relevant to the control of the main vector species are emphasised. Different lines of evidence suggest that Triatoma dimidiata is not native to Ecuador-Peru, and that synanthropic populations of Rhodnius ecuadoriensis in southern Ecuador-northern Peru might be isolated from their sylvatic conspecifics. Local eradication of T. dimidiata and these R. ecuadoriensis populations might therefore be attainable. However, the presence of a wide variety of native species indicates the necessity for a strong longitudinal surveillance system.
Key words: Triatominae - biogeography - Chagas disease - control - Triatoma dimidiata - Rhodnius ecuadoriensis - Ecuador
Mem. Inst. Oswaldo Cruz vol.96 no.5 Rio de Janeiro July 2001
Around 3 million people live under risk conditions for Trypanosoma cruzi transmission in Ecuador; prevalence estimates indicate that ~150,000 people are already infected (Aguilar et al. 1999). Sixteen triatomine species have been reported from the country (excluding doubtful records of Triatoma infestans and Rhodnius prolixus) (Aguilar et al. 1999). At least 13 of these species (see Tables I-III) are actual or potential vectors of Chagas disease (Lent & Wygodzinsky 1979, WHO 1991, Abad-Franch 2000). This complex situation is currently being investigated in the context of the National Programme for Chagas Disease Control in Ecuador. Our aim is to contribute to these efforts by analysing and completing the relevant information about Chagas disease triatomine vectors in Ecuador.
From 1998 to 2000, and as part of our research on the epidemiological significance of Rhodnius species in Ecuador and Peru, we undertook a revision of the Triatominae kept at various important entomological collections. During that revision, new data on distribution of some species in Ecuador became apparent. We added entomological records from our own fieldwork and from research being carried out by Ecuadorian colleagues. Here we report those new records, together with previously published data, and analyse them in relation to the main ecological and epidemiological traits of the different species. Finally, recommendations on vector control strategies are put forward.