Serological, molecular and entomological surveillance demonstrates widespread circulation of West Nile virus in Turkey.

Koray Ergunay,Kerem Oter,Bulent Alten,Sepandar Gargari,Seda Tezcan,Gürol Emekdas,Ozge Erisoz Kasap,Mehmet Cabalar,Taner Karaoglu,Aykut Ozkul,Yakup Yildirim,Filiz Gunay,Remi Charrel

doi:10.1371/journal.pntd.0003028

Abstract

West Nile virus (WNV), a mosquito-borne flavivirus with significant impact on human and animal health, has recently demonstrated an expanded zone of activity globally. The aim of this study is to investigate the frequency and distribution of WNV infections in potential vectors and several mammal and avian species in Turkey, where previous data indicate viral circulation. The study was conducted in 15 provinces across Turkey during 2011–2013. In addition, the entomological study was extended to 4 districts of the Turkish Republic of Northern Cyprus. WNV exposure was determined in humans, horses, sheep and ducks from Mersin, Sanliurfa, Van and Kars provinces of Turkey, via the detection of neutralizing antibodies. WNV RNA was sought in human and equine samples from Mersin, Adana and Mugla provinces. Field-collected mosquitoes from 92 sites at 46 locations were characterized morphologically and evaluated for viral RNA. Neutralizing antibodies were identified in 10.5% of the 1180 samples studied and detected in all species evaluated. Viral nucleic acids were observed in 5.9% of 522 samples but only in horses. A total of 2642 mosquito specimens belonging to 15 species were captured, where Ochlerotatus caspius (52.4%), Culex pipiens sensu lato (24.2%) comprise the most frequent species. WNV RNA was detected in 4 mosquito pools (1.9%), that comprise Oc. caspius Cx. pipiens s.l. and DNA barcoding revealed the presence of Cx. quinquefasciatus and Cx. perexiguus mosquitoes in infected Culex pools. All WNV partial sequences were characterized as lineage 1 clade 1a. These findings indicate a widespread WNV activity in Turkey, in Eastern Thrace and Mediterranean-Aegean regions as well as Southeastern and Northeastern Anatolia.

Highlights

West Nile virus (WNV) is a re-emerging arthropod-borne virus with a significant impact on human and animal health [1]
Limited information is available on WNV epidemiology in Turkey, located in the endemic zone of the agent around the Mediterranean Sea
Field-captured mosquito specimens demonstrated the presence of major WNV vectors among 15 species identified

Summary

Introduction

West Nile virus (WNV) is a re-emerging arthropod-borne virus with a significant impact on human and animal health [1]. The global epidemiology of WNV has drastically changed during the last decades, with the introduction and spread of the virus in the American continent and increased reporting of virus activity in Europe, probably influenced by the interaction of factors such as global warming, demographic changes and modern transportation [3,4,5]. Since 1990s, the human disease incidence of WNV strains with probable African origin have increased in parts of Russia and southern, central and eastern Europe, with large outbreaks of notable severity occurring in Romania, Russia, Israel, Italy and Greece [3]. In the United States, WNV resurgence was observed in 2012 after several years of decreasing incidence [5]

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