SERO-PREVALENCE OF WEST NILE VIRUS IN POULTRY CORRELATING WITH MOSQUITOES IN URBAN AND PERI-URBAN AREAS OF GUWAHATI
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Date
2019-07
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College of Veterinary Science, Assam Agricultural University, Khanapara, Guwahati
Abstract
West Nile virus (WNV), an arthropod-borne virus of public health importance is a member of the genus Flavivirus belonging to the Japanese encephalitis virus antigenic complex under family Flaviviridae. In Assam, although poultry rearing has traditionally been popular, most of the farmers lack proper scientific knowledge and technique, thereby increasing their risk to contact with different zoonotic diseases. The present investigation was carried out from April, 2018 to March, 2019 to collect baseline data on poultry farms, study the sero-prevalence of WNV in chicken, study the density pattern and determine the infection rate of mosquitoes with WNV and to prepare WNV prevalence map in urban and peri-urban areas of Guwahati. A total 8 locations comprising of 4 locations each for urban areas viz., Chandmari, Hatigaon, Noonmati, Khanapara, and peri-urban areas of Guwahati viz., Jugukuchi, Kamalajari, Garal and Gadebari were selected.
Baseline data revealed that most of the farmers were educated up to higher secondary (41.67%) level and below 46 years (66.67%), rearing both broiler and indigenous chickens in moderately clean or unhygienic farms (83.33%) with 58.33% of the birds being dirty. Presence of in-contact other animals, including cows, pigs, goats, ducks, quails, pigeons and dogs were recorded in 66.67% of farms and majority of the farmers (54.17%) did not consult veterinarian. Vaccination was practiced in 91.67% farms and the farmers used unsafe method of waste and carcass disposal. Screening of a total of 864 serum samples of chickens by ELISA and further confirmation by HI revealed the overall sero-prevalence of WNV to be 3.13%, with 0.69% sero-positivity in urban compared to 5.56% in peri-urban areas. WNV sero-prevalence was recorded in 1 urban and 3 peri-urban locations showing peak sero-prevalence during monsoon (7.29%). Highest sero-prevalence of WNV was recorded in Jugukuchi (11.11%) of peri-urban Guwahati. Sero-prevalence of WNV was significantly very high (P<0.001) in farms having in-contact other animals, stagnant water and agriculture. The association between flock size and sero-prevalence of WNV was found highly significant (P<0.01). A total of 21,267 mosquitoes trapped during 1 year study period belonged to 5 genera viz. Culex, Mansonia, Aedes, Anopheles and Armigeres and 12 different species. Density pattern of mosquitoes revealed Cx. quinquefasciatus, Cx. vishnui group, Ma. uniformis, Cx. bitaeniorhynchus, Ar. subalbatus, Ma. annulifera and Ae. albopictus to be dominant species with most predominant species being Cx. quinquefasciatus (36.51%). Real time one-step RT-PCR of a total of 288 pooled mosquito samples detected NS5 gene of Flavivirus in 26 Culex and Mansonia mosquito pools. Sanger sequencing of representative amplicons of Flavivirus appeared to be negative for WNV but positive for Usutu virus, a mosquito-borne flavivirus which is closely related to WNV. The farms with WNV sero-prevalence in urban and peri-urban areas of Guwahati were spotted and mapped based on their latitude and longitude, which will be of immense support in future for strategic planning to control vector-borne diseases in those areas.