Flock-Based Surveillance for Low Pathogenic Avian Influenza Virus in Commercial Breeders and Layers, Southwest Nigeria

Abstract

Background: Flock surveillance systems for avian influenza (AI) virus play a critical role in countries where vaccination is not practiced so as to establish the epidemiological characteristics of AI needed for the development of prevention and control strategies in such countries. Materials and Methods: As part of routine AI monitoring in southwest Nigeria, a competitive ELISA was used for detecting influenza A virus antibodies in the sera of 461 commercial breeder and layer birds obtained from different flocks in Oyo State, Nigeria while haemagglutination inhibiting antibodies against low pathogenic AI viruses (LPAIVs) were detected using H5N2, H7N7 and H9N2 subtype-specific antigens. Suspensions prepared from cloacal swabs were tested for AI virus RNA using reverse transcriptase-polymerase chain reaction. Results: Results showed that influenza A virus antibody prevalence was 12.8% and 9.3% for breeders and layers, respectively while HI assay revealed 22.0%, 2.0% and 78.0% prevalence of LPAIV H5N2, H7N7 and H9N2 antibodies respectively. All cloacal swab suspensions were negative for AIV RNA. Conclusion: Since LPAI infections result in decreased or complete cessation of egg production in breeder and layer birds, increased infection severity due to co-infection with other poultry viruses have occasionally been transmitted to humans, the detection of LPAIV H5N2, H7N7 and H9N2 antibodies in these birds is of both economic and public health significance. These findings underscore the need for continuous flock monitoring as part of early warning measure to facilitate rapid detection and sustainable control of AI in Nigerian poultry.

Detection of antibodies to H5 and H9 subtypes of influenza viruses in wild birds in Zaria, Nigeria

“…However, current evidence reveals that they could potentially play a significant role in the future emergence of the influenza pandemic, either directly as a H9 AIV subtype virus or as a result of the donation of internal genes to HPAI pandemic subtypes (Peacock et al, 2019b). The finding in this study is similar to that reported by Oluwayelu et al (2017), who detected H9 influenza virus antibodies in commercial breeders and layers birds in South western Nigerian States.…”

A Global Perspective on H9N2 Avian Influenza Virus

“…Finally, there are a pair of studies showing high seropositivity against H9N2 in Nigerian poultry and agricultural workers, however, no virus has been isolated from this country [57,58]. Although surveillance for HPAIVs is ongoing in Nigeria, it is unclear whether protocols are used that would pick up the presence (or absence) of H9N2 viruses, therefore it remains unclear whether the virus is/was present in this region.…”

H9 Influenza Viruses: An Emerging Challenge

“…Recently, one isolate of an H9 related to the Korean subclade A h9.2.2.2 was reported in poultry from North Korea (Zhang et al 2017b). Additional studies suggest serological evidence of H9N2 IAVs in poultry in Romania, Nigeria, Laos, and Thailand, but lineage characterization is lacking (Sonnberg et al 2012;Oluwayelu et al 2017;Coman et al 2018;Karlsson et al 2019).…”