Diversidade e sazonalidade de Anopheles sp. (Diptera : Culicidae) com Ãnfase na prevalÃncia de malÃria em Roraima / Diversity and seasonality of anopheles sp. (diptera: Culicidae) with emphasis on malaria prevalence in Roraima

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

Malaria remains one of the most important infectious diseases in the world. It is estimated that 400 million cases occur every year, especially in tropical and subtropical regions. In this project we have studied entomological and epidemiological aspects of transmission in the State of Roraima, in Northern Amazon, Brazil. The region presents a diversity of ecosystems. Initially the distribution of the Anopheline species in the area are described. We report immunologic vector incrimination tests for these species. Further studies were performed in two areas during one year. One site is an agricultural settlement in the tropical forest. The other area borders a gallery forest in the savanna. Seasonal density and geographical fluctuations in larvae and adult mosquitoes were analyzed. We determined and characterized breeding sites for local vectors, their dispersion capabilities, hourly biting activity, age structure and survival curves. Different methods for age determination were compared. The impact of deforestation on larval densities was evaluated. The finding of infected An. albitarsis s.l. suggest it is an important vector, besides An. darlingi. Survival rates were well correlated to the ones reported in the literature and seasonal fluctuation explained the previously described variation. Longevity increased during the dry season in the forest, which was correlated to increases in number of malaria cases. The duration of the gonotrophic cycle of An. darlingi was longer in the forest than in the savanna. Larvae of this species were clustered near human houses, but deforestation had a negative effect on the prevalence of its larvae. Construction of artificial dams provided breeding sites for An. darlingi, permitting year-long malaria transmission. However, limited dispersion of adults under natural conditions impeded propagation of cases away from the breeding areas. Adult densities of An. darlingi showed a peak at the end of the dry season in the forest, while peaks where observed during the rainy season in the savanna. Anopheles albitarsis s.l. densities in the savanna were also correlated with increased raining. Survival rates and larval and adult densities were correlated to provide an ample model of malaria transmission. Malaria transmission capacities would follow diverging trends according to the drainage system of the area. Finally, we describe the occurrence of a mosquito parasite, without previous records for Latin America, that could cause pathological effects on female ovarian development in An. darlingi

ASSUNTO(S)

densidade capacidade vetorial estrutura etÃria plasmodium zoologia

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