High prevalence of malaria infection in Amazonas state, Venezuela

Abstract

SUMMARYThis study was carried out to determine the incidence of malaria in an endemic region of Amazonas State, Venezuela. For this, 200 random samples were collected from symptomatic and asymptomatic individuals from San Fernando de Atabapo and Santa Barbara. Epidemiological factors were related to malaria infection, which was diagnosed by microscopy observation and amplification of the 18S rDNA sequence by PCR. Malaria prevalence in these populations was 28.5%, whilst P. vivax and P. falciparum prevalences were 12 and 17%, respectively. No infection by P. malariae was found. A mixed infection was found on an asymptomatic individual. Prevalence patterns differed between age groups depending on the Plasmodium species. We found that 34.8% of the P. vivax and 15.2% of the P. falciparum infections were asymptomatic. The use of nets was helpful to prevent P. vivax infection, but did not protect against P. falciparum infection. The results suggest the presence of more than one mosquito vector in the area, displaying a differential pattern of infection for each Plasmodium species. There appear to be risk factors associated with malaria infections in some individuals. The population based approach and PCR diagnosis improved the accuracy of the statistical analysis in the study.

High Rates of Asymptomatic, Sub-microscopic Plasmodium vivax Infection and Disappearing Plasmodium falciparum Malaria in an Area of Low Transmission in Solomon Islands

“…Whereas asymptomatic P . vivax infections have been commonly found in areas of high transmission [ 12 , 35 , 36 ], the advent of molecular diagnosis has revealed that even at low transmission the majority of infections in cross-sectional surveys are symptomless [ 11 , 37 , 38 ], including in the previous surveys in Temotu [ 9 ] and Isabel [ 8 ] where 97.1% and 92.9% of P . vivax infected individuals infections were asymptomatic, respectively.…”

Malaria seroprevalence in blood bank donors from endemic and non-endemic areas of Venezuela

“…The prolonged contact of individuals to malaria parasites has been reported to decrease parasite densities and host symptoms; further, there are reports of infected asymptomatic patients in endemic areas of Venezuela that were not properly diagnosed by microscopic examination (Postigo et al 1998, Rodulfo et al 2007b). In the Brazilian Amazon, a PCR analysis of 400 samples collected from four blood transfusion centres, found frequencies of malaria-infected blood donors ranging from 1-3% (Fugikaha et al 2007).…”

Malária em gestantes no município de Cruzeiro do Sul pertencente à região amazônica brasileira

“…As características epidemiológicas são semelhantes em todos os países, com regiões apresentando graus variados de risco de transmissão, apresentando ascensão e queda dos casos. Em determinadas situações a malária torna-se ré-emergentes, provocando epidemias, demonstrando a interação de fatores que influenciam na epidemiologia da malária, sendo observado o decréscimo dos casos de P. falciparum, mas manutenção dos casos de P. vivax na maioria das análises (RODULFO et al, 2007 ;ROPER et al, 2000;CHOWELL et al, 2009 ;SUTTON, et al, 2009;RODRIGUEZ VELASQUEZ, 2010).…”