Seroprevalence of Avian Influenza Viruses in Asymptomatic Backyard Poultry Birds in District Multan, Pakistan

Abstract

Avian influenza viruses (AIVs) are the serious health concern throughout the globe and induce heavy economic losses in poultry industry. In the rural settings, the domestic birds are neglected for avian influenza (AI) vaccination while they are directly connected with migratory carrier birds throughout their life. Keeping in view this study was design. Four Tehsils of district Multan were selected to investigate asymptomatic backyard poultry birds for presence of AIVs. For this purpose, a total of 213 birds were randomly selected and from each bird sera, oro-pharyngeal and cloacal swab samples were collected in sterile containers. About 13.61% of the samples were found seropositive by using commercially available ELISA kit. The supernatants from oro-pharyngeal and cloacal swabs of the seropositive samples were separated and divided into two segments; one was used directly to detect AI viral genome through RTPCR while other segment was used for viral inoculation into the embryonated chicken eggs. The direct detection through RT-PCR confirmed H9 gene from cloacal swab samples in 6.9% of the seropositive sample while we could not confirm any of the oro-pharyngeal samples for H9 gene through direct molecular detection. The cultivated oro-pharyngeal and cloacal swab samples were not found positive upon re-confirmation from allantoic fluid through RT-PCR by using same specific set of primers. This study concludes that asymptomatic backyard poultry birds can carry AI viruses and act as potential reservoirs that might be responsible for recurrent episodes of AI outbreaks in a region. The viral shedding through oral and/or cloacal route may be the best way to disseminate infection towards the susceptible ones. Lastly, this study urges to vaccinate the rural poultry birds to prevent further spread of the AIVs that interrupt with commercial poultry production system and also with the community.