Malaria vectors in the Brazilian Amazon: Anopheles of the subgenus Nyssorhynchus

Abstract

SUMMARYVarious species of Anopheles (Nyssorhynchus) were studied in the Amazon with the objective of determining their importance as malaria vectors. Of the 33 known Anopheles species occurring in the Amazon, only 9 were found to be infected with Plasmodium. The different species of this subgenus varied both in diversity and density in the collection areas. The populations showed a tendency towards lower density and diversity in virgin forest than in areas modified by human intervention.The principal vector, An. darlingi, is anthropophilic with a continuous activity cycle lasting the entire night but peaking at sunset and sunrise. These species (Nyssorhynchus) are peridomiciliary, entering houses to feed on blood and immediately leaving to settle on nearby vegetation.Anopheles nuneztovari proved to be zoophilic, crepuscular and peridomiciliary. These habits may change depending on a series of external factors, especially those related to human activity.There is a possibility that sibling species exist in the study area and they are being studied with reference to An. darlingi, An. albitarsis and An. nuneztovari. The present results do not suggest the existence of subpopulations of An. darlingi in the Brazilian Amazon.

Urban and suburban malaria in Rondônia (Brazilian Western Amazon) II: perennial transmissions with high anopheline densities are associated with human environmental changes

“…Similar low infection indexes were found in previous studies in dry land areas and riverine rural areas of Rondônia (Gil et al 2003). In a recent review, Tadei and Dutary-Thatcher (2000) registered infection index of 0.2 to 2.0 for An. darlingi captured in various endemic areas of Brazilian Amazon, including sites close to those of the present study.…”

“…An. darlingi is the main vector in all Amazon areas (Deane 1988, Lourenço-de-Oliveira 1988 Tadei & Dutary-Thatcher 2000) and it is the dominant species in both model areas (Gil et al 2003). However, while its favorable breeding sites are always large collections of water rich in aquatic vegetation and exposed to sun, they drastically differ in origin and development in different areas.…”

“…darlingi. Therefore, high anopheline densities are observed at the end of rainy season and beginning of the dry season explaining the malaria outbreaks in the dry season (Camargo et al 1994, 1996, Tadei & Dutary-Thatcher 2000.…”

Malaria entomological inoculation rates in gold mining areas of Southern Venezuela

“…darlingi bites/person/night in different geographical areas (Rubio-Palis 1995, Magris et al 2007, Moreno et al 2007). In Brazil, Tadei and Dutary-Thatcher (2000) reported biting rates that varied from 0.13-53, whereas Galardo et al (2007) reported much higher rates in AP, varying between villages from 53.9-837.7. The highest biting rate reported for An.…”

Self‐reported compliance with last malaria treatment and occurrence of malaria during follow‐up in a Brazilian Amazon population

“…The level of malaria transmission is considered hypo-endemic. The main malaria vector in this area, as in most Amazon regions, is Anopheles darlingi, which is well known for its high vectorial capability (Tadei & Dutary 2000). There are two malaria laboratories providing diagnostic services and complete treatment for malaria 7 days a week.…”