title: Serological evidence of widespread West Nile virus and Japanese encephalitis virus infection in native domestic ducks (Anas platyrhynchos var domesticus) in Kuttanad region, Kerala, India.
abstract: Birds can act as reservoirs of West Nile virus (WNV) with a key role in its epidemiology. WNV lineage 1 associated fatal cases of human encephalitis in 2011 and acute flaccid paralysis in 2013 were reported in Alappuzha district, Kerala, India. But no information is available on WNV circulation in domestic ducks, which are abundant, cohabit with humans and occupy wetlands and water bodies in the region. To determine the extent of WNV infection, we investigated 209 sera, 250 oral and 350 cloacal swab samples from local Chara and Chemballi domestic ducks (Anas platyrhynchos var domesticus) in the districts of Alappuzha, Kottayam, Kollam and Pathanamthitta collected during January and March 2015. The serum samples were tested for WNV antibodies first by a competition ELISA and then by a micro virus neutralization test (micro-VNT), while oral and cloacal swabs were subjected to WNV real-time RT-PCR. Ninety five ducks showed evidence of flavivirus antibodies by ELISA. End point neutralizing antibody titre against WNV and Japanese encephalitis virus (JEV) revealed WNV specific antibodies in 24 (11.5%) ducks in 3 districts, JEV specific antibodies in 21 (10%) ducks in 2 districts and flavivirus specific antibodies in 19 (9%) ducks. However, no WNV genomic RNA could be detected. The results of this study demonstrate evidence of widespread WNV and JEV infection in domestic ducks in Kuttanad region, Kerala with a higher seroprevalence to WNV than JEV. Additionally, it highlights the utility of domestic ducks as a surveillance tool to detect WNV/JEV circulation in a region.
authors.affiliation: ICAR-National Institute of High Security Animal Diseases, Anand Nagar, Bhopal, Madhya Pradesh 462 022, India.
authors.forename: Semmannan
authors.initials: S
authors.lastname: Kalaiyarasu
authors.affiliation: ICAR-National Institute of High Security Animal Diseases, Anand Nagar, Bhopal, Madhya Pradesh 462 022, India. Electronic address: mishranir@rediffmail.com.
authors.forename: Niranjan
authors.initials: N
authors.lastname: Mishra
authors.affiliation: ICAR-National Institute of High Security Animal Diseases, Anand Nagar, Bhopal, Madhya Pradesh 462 022, India.
authors.forename: Rohit Kumar
authors.initials: RK
authors.lastname: Khetan
authors.affiliation: ICAR-National Institute of High Security Animal Diseases, Anand Nagar, Bhopal, Madhya Pradesh 462 022, India.
authors.forename: Vijendra Pal
authors.initials: VP
authors.lastname: Singh
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood; D002988:Cloaca / Q000821:virology; D004197:Disease Reservoirs; D004372:Ducks; D004664:Encephalitis Virus, Japanese / Q000276:immunology* / Q000302:isolation & purification; D004672:Encephalitis, Japanese / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007194:India / Q000453:epidemiology; D009500:Neutralization Tests; D011201:Poultry Diseases / Q000453:epidemiology* / Q000821:virology; D060888:Real-Time Polymerase Chain Reaction; D016036:Seroepidemiologic Studies; D014901:West Nile Fever / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D014902:West Nile virus / Q000276:immunology / Q000302:isolation & purification
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral
keywords: Domestic ducks; India; Japanese encephalitis virus; Kerala; Neutralizing antibodies; West Nile virus