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Memórias do Instituto Oswaldo Cruz
Fundação Oswaldo Cruz, Fiocruz
ISSN: 1678-8060
EISSN: 1678-8060
Vol. 102, No. 3, 2007, pp. 303-311
Bioline Code: oc07052
Full paper language: English
Document type: Research Article
Document available free of charge

Memórias do Instituto Oswaldo Cruz, Vol. 102, No. 3, 2007, pp. 303-311

 en Vector bionomics and malaria transmission in the Upper Orinoco River, Southern Venezuela
Magris, Magda; Rubio-Palis, Yasmin; Menares, Cristóbal & Villegas, Leopoldo

Abstract

A longitudinal epidemiological and entomological study was carried out in Ocamo, Upper Orinoco River, between January 1994 and February 1995 to understand the dynamics of malaria transmission in this area. Malaria transmission occurs throughout the year with a peak in June at the beginning of the rainy season. The Annual Parasite Index was 1,279 per 1,000 populations at risk. Plasmodium falciparum check for this species in other resources infections accounted for 64% of all infections, P. vivax for 28%, and P. malariae for 4%. Mixed P. falciparum/ P. vivax check for this species in other resources infections were diagnosed in 15 people representing 4% of total cases. Children under 10 years accounted for 58% of the cases; the risk for malaria in this age group was 77% higher than for those in the greater than 50 years age group. Anopheles darlingi check for this species in other resources was the predominant anopheline species landing on humans indoors with a biting peak between midnight and dawn. A significant positive correlation was found between malaria monthly incidence and mean number of An. darlingi caught. There was not a significant relationship between mean number of An. darlingi and rainfall or between incidence and rainfall. A total of 7295 anophelines were assayed by ELISA for detection of Plasmodium circumsporozoite (CS) protein. Only An. darlingi (55) was positive for CS proteins of P. falciparum (0.42%), P. malariae (0.25%), and P. vivax-247 (0.1%). The overall estimated entomological inoculation rate was 129 positive bites/person/year. The present study was the first longitudinal entomological and epidemiological study conducted in this area and set up the basic ground for subsequent intervention with insecticide-treated nets.

Keywords
Plasmodium falciparum - Plasmodium vivax - Plasmodium malariae - malaria incidence - Anopheles darlingi - biting activity - sporozoite rate - entomological inoculation rate - Venezuela

 
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