Land use, species diversity and malaria transmission in southern Venezuela.  Y. Rubio-Palis, J. E. Moreno, M. Magris, M. Bevilacqua y D. Medina.

Southern Venezuela has been considered an area of high risk for malaria. This vast region has been characterized as interior lowland forest malaria, where the main vector is Anopheles darlingi. Changes in land use as a result of anthropogenic factors have created different ecological and epidemiological situations. The Caura river basin is inhabited by 4,050 Amerindians of the Ye´kwana and Sanema ethnic groups spread through out some 47,000 km2 of forested areas. Malaria incidence during 2005 was less than 20 cases per 1,000 population. Agriculture is slash and burn, creating artificial savannas. Anopheline larval habitats are mainly back swamp forest and so far 6 anopheline species have been collected; the most frequent was An. oswaldoi; while human landing catches of adult females resulted in 4 species where the most abundant was An. darlingi. The Upper Orinoco River covers some 82,662 km2 ; and is inhabited by approximately 15,000 Amerindians of the Yanomami ethnic group. Reported malaria incidence during 2005 was 47 cases per 1,000 population. The region is covered mainly by dense forests and savannas. Agricultural practices are mainly based on slash and burn. Larval habitats are mainly back swamp forests and pools, and the most frequent anopheline species collected was An. oswaldoi. Nevertheless, inside human dwellings almost 99% of collected adult mosquitoes were An. darlingi. A different situation is found in the municipality of Sifontes where dramatic environmental changes have occurred during the past 2 decades with massive deforestation for mining, logging and urbanization. The municipality covers 24,392 km2 and the population fluctuate around 60,000. During 2005, 216 cases of malaria per 1,000 population were reported. Gold mines dug outs were the most productive sites in terms of immature abundance and species diversity; 14 species have been collected. Adult collections yielded 6 species; the most abundant species were An. marajoara, An. darlingi and An. neomaculipalpus. All 3 species tested positive for circumsporozoite Plasmodium spp. protein and hence, might be involved in the transmission of the parasite. In conclusion, anthropogenic changes in forest areas introduces heterogeneity, creating new larval habitats for anophelines resulting in an increase of species diversity and the emergence of vectors of malaria parasites (An. marajoara and An. neomaculipalpus). Project funded by CE- CDC/2005/106-946.

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