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Seroprevalence of arbovirus in Ecuador: implications for improved surveillance

Abstract:

Introduction: Arthropod-borne viruses (arbovirus) cause morbidity and mortality of 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, investigate 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%-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%-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. Equine and hamsters showed antibodies to Alphavirus in all locations; two hamsters seroconverted to YFV in the Amazonia. Conclusions: The result shows YFV-vaccination history and suggest the activity arboviruses no included in the current surveillance scheme. Enhanced arbovirus and mosquitoes surveillance, continued YFV-vaccination and evaluation of its coverage/effectiveness are recommended.