RESUMO
Abstract | Introduction: Arthropod-borne viruses (arboviruses) cause morbidity and mortality in humans and domestic animals worldwide. The percentage of population immunity or susceptibility to these viruses in Ecuador is unknown. Objectives: To investigate the proportion of Ecuadorian populations with IgG antibodies (Abs) (past exposure/immunity) and IgM Abs (current exposure) against flaviviruses and alphaviruses and to study the activity of these viruses in Ecuador. Materials and methods: During 2009-2011, we conducted a serosurvey for selected arboviruses in humans (n=1,842), equines (n=149), and sentinel hamsters (n=84) at two coastal locations and one in the Amazon basin (Eastern Ecuador) using enzyme-linked immunosorbent assay and hemagglutination inhibition test. Results: From 20.63% to 63.61% of humans showed IgG-antibodies for the flaviviruses: Dengue virus (DENV), yellow fever virus (YFV) Saint Louis encephalitis virus, and West Nile virus (WNV); from 4.67% to 8.63% showed IgG-Abs for the alphaviruses: Venezuelan equine encephalitis virus, eastern equine encephalitis virus, and western equine encephalitis virus. IgM-Abs were found for DENV and WNV. Equines and hamsters showed antibodies to alphaviruses in all locations; two hamsters seroconverted to YFV in the Amazonia. Conclusions: The results show a YFV vaccination history and suggest the activity of arboviruses not included in the current surveillance scheme. Enhanced arbovirus and mosquito surveillance, as well as continued YFV vaccination and evaluation of its coverage/ effectiveness, are recommended.
Resumen | Introducción. Los virus transmitidos por artrópodos (arbovirus) causan morbilidad y mortalidad en humanos y animales domésticos mundialmente. Se desconoce el porcentaje de inmunidad o vulnerabilidad de la población ecuatoriana ante estos virus. Objetivos. Investigar la proporción de poblaciones ecuatorianas con anticuerpos IgG (exposición o inmunidad pasada) y anticuerpos IgM (exposición reciente) contra flavivirus y alfavirus, e investigar su actividad en Ecuador. Materiales y métodos. Entre 2009 y 2011, se llevó a cabo una encuesta serológica para arbovirus en humanos (n=1.842), equinos (n=149) y hámsters centinela (n=84) en dos localidades costeras y en una en la Amazonía, utilizando la prueba ELISA (Enzyme-Linked ImmunoSorbent Assay) y la prueba de inhibición de la hemaglutinación. Resultados. Entre el 20,63 y el 63,61 % de los humanos registraron IgG contra el virus del dengue (DENV), el de la fiebre amarilla (YFV), el de la encefalitis de San Luis y el del Nilo Occidental (WNV); entre 4,67 y 8,63 % tenían IgG para los virus de la encefalitis equina venezolana, de la encefalitis equina del este y de la encefalitis equina del oeste. Se encontró IgM para DENV y WNV. En los equinos y en los hámsters se encontraron anticuerpos contra alfavirus en todas las localidades muestreadas; dos hámsters mostraron seroconversión a YFV en la Amazonía. Conclusiones. Los resultados del estudio evidenciaron los antecedentes de vacunación contra el YFV y sugieren la actividad de arbovirus no incluidos en el esquema de vigilancia actual. Se recomienda ampliar la vigilancia de arbovirus y mosquitos, continuar con la vacunación contra el YFV, y evaluar su cobertura y efectividad.
Assuntos
Arbovírus , Vírus do Nilo Ocidental , Vírus da Febre Amarela , Vírus da Dengue , Vírus da Encefalite Equina do Leste , Vírus da Encefalite Equina VenezuelanaRESUMO
At the Leopoldo Izquieta Perez National Institute of Hygiene and Tropical Medicine in Guayaquil, Ecuador, between November 1983 and February 1985 an evaluation was done of the serological response of two groups, of 19 volunteers each, who received rabies suckling mouse brain (SMB) vaccine produced by that institution and quality- controlled by the PAHO/WHO Pan Américan Zoonoses Center. Two postexposure treatment schemes were used: one group received 14 doses of rabies SMB vaccine (one per day) plus three boosters at 10, 20, and 90 days after the last dose of the initial series; the other group recieved six doses (one per day) and two boosters at 20 and 90 days after completing the initial series. It was not possible to demonstrate statistically significant differences between the median titers of the rabies neutralizing antibody in the two groups at 32, 98, and 180 days after the beginning of the two treatments. The results of this study could serve as a basis for the health authorities of Ecuador in their adoption of a limited vaccination scheme that is more innocuous, effective, and economical than the scheme presently applied in that country