Inquérito soroepidemiológico dos vírus das encefalites equinas do leste e do oeste em população de área sob influência do lago da hidrelétrica de Tucuruí - Pará

Abstract

The EEEV and WEEV are Arboviruses of the family Togaviridae, genus Alphavirus, which measure 60-70 nm in diameter and is composed of transmembrane glycoproteins E1 and E2, the capsid protein or the nucleocapsid, which is derived from the lipid bilayer of the host, and a single molecule single-stranded RNA and positive polarity. They are transmitted by mosquitoes, primarily Culex, Aedes, whose natural reservoir of birds and humans as accidental hosts, horses and other small mammals. Infected individuals are asymptomatic or develop flu-like illness that may progress to severe neurological disease with a prevalence in humans in North America and horses across America. The fatality rate for EEE in humans is 30% and 40% for WEE is 10%. The study was observational, cross-sectional analytical study carried out in individuals of both sex, aged over 18, resident of the lake Tucuruí power plant and from the RDS and Alcobaça Pucurui-Ararão. The collection of blood samples and filling in the questionnaire were performed at two different times, in September/2008 and March/2009. All samples were analyzed by the Evandro Chagas Institute where they were tested with hemagglutination inhibition for detection of antibodies against 19 types of Arboviruses. Data analysis was descriptive and analytical, and used the chi-square or Fisher exact test to verify the statistical significance of associations between variables of the study with an alpha level of 0,05. Altogether 365 samples were analyzed, which showed 1.1% positive for EEE and 1.6% for WEE. Most positive cases had poor sanitary conditions (100% for EEA and 83.3% for WEE) using cesspits (75% to 100% for EEE and WEE) and water from rivers and / or lakes ( 100% to 83.3% for EEE and WEE). The positive cases for EEE and WEE were related to other Arboviruses, where 100% of EEE and WEE were positive for HI-Flavivirus, 25% for EEE virus Maguari, HI-Mayaro and HI-Oropouche and 33.3 % of WEE to HI-Mayaro and 16.7% for the virus Guaroa. The study confirmed the presence of EEE virus and WEE in the region and some socio-environmental factors such as use of cesspits and poor sanitation conditions, conducive to public exposure to vectors and raised the possibility of cross protection with other alphaviruses.