Ecologic observations on anopheline vectors of malaria in the Brazilian Amazon.

Abstract

Human intervention in the Brazilian Amazon region promotes contacts between humans and vectors that may favor the propagation of anopheline mosquitoes and the spread of malaria in the absence of planning and infrastructure to control this disease. Vector ecology studies were carried out to determine the risk areas. These data should help in designing appropriate malaria control measures. Data from 14 different regions are reported. Vectors are able to adapt to different environments, which made it necessary to study each area. The parameters studied were Anopheles breeding sites, species distribution, incidence, feeding preferences, hours of maximum activity of adult mosquitoes, seasonality, resting places, and the presence of Plasmodium. Species complexes were also studied. Anopheles darlingi may be responsible for maintaining malaria in human populations in this region. A reduction in the population density of A. darlingi in a particular geographic area can sometimes cause the disappearance of malaria. This species feeds at night but has a peak of activity at the beginning of the evening and another at dawn. Other species are mainly crepuscular and all anophelines demonstrated pronounced exophilia. The timing of feeding activities was found to vary in areas altered by human intervention and also depended on the time of the year and climatic conditions. The larvae were more abundant in the rivers with a less acidic pH and rural areas showed the highest larval index.

Mitochondrial DNA Detects a Complex Evolutionary History with Pleistocene Epoch Divergence for the Neotropical Malaria Vector Anopheles nuneztovari Sensu Lato

“…10 However, mosquitoes collected from the central Amazonian region have been mainly zoophagic and exophilic. 7 In the present study and in the study of Scarpassa and others, 27 samples from these two regions had no shared haplotypes and were recognized as distinct lineages by Conn and others, 26 which could indicate a barrier to gene flow. If this suggestion is correct, this finding may explain distinct behavioral patterns of these mosquitoes.…”

“…from Amazonian Brazil seems not to sustain malaria transmission or to be incapable of causing malaria outbreaks in the absence of the primary vector Anopheles darlingi Root. 7,11 Approximately half of the anopheline vector species belong to sibling/cryptic species complexes. 12 The presence of complexes can cause heterogeneous patterns of malaria transmission, sometimes resulting in reduced vector control effectiveness or even in failure.…”

“…nuneztovari has been found infected with Plasmodium sp. [5][6][7][8][9] Although most Brazilian populations are exophagic and mainly zoophilic, with a peak biting time around sunset, in some localities in Pará state, anthropophagic and endophagic behaviors have been encountered, 10 and it has been incriminated as a local vector in Amapá State. 9 Overall, An.…”

Malaria entomological inoculation rates in gold mining areas of Southern Venezuela

“…Nevertheless, low biting densities (5-10 bites/person/ night) seem to be characteristic of An. darlingi throughout its range of distribution (Roberts et al 1987, Tadei et al 1998, Soares et al 2003, Brochero et al 2005, Vittor et al 2006). There are reports in Venezuela of biting rates that varied from 5.8-1,265 An.…”

Meio ambiente e saúde: metodologia para análise espacial da ocorrência de malária em projetos de assentamento

“…Além disso, foram utilizadas informações etnográficas, coletadas de 1985 a 1995 (Castro et al, 2006a (DEANE, 1947;COVA-GARCIA, 1961; VAN THIEL, 1962;TADEI et al, 1998). O segundo diz respeito às características físicas dos lotes em Machadinho (desenho irregular e tamanho médio) e suas implicações na definição da área de vizinhança no entorno de cada lote (CASTRO et al, 2006b).…”