EPIDEMIOLOGICAL INVESTIGATION OF H9N2 VIRUS CIRCULATION IN BACKYARD POULTRY FARMS AND HUMANS IN A RURAL COMMUNITY, BANGLADESH

Abstract

Intro: The avian influenza virus (AIV) subtype H9N2 is endemic in domestic poultry in most Asian countries and occasionally spillover to humans. On the report of a suspected human A/H9 outbreak, a multidisciplinary team investigated the source of infection and extent of the outbreak in a rural village between February 2-4, 2017. Methods: We surveyed the community within a 1km radius of the index case house. Anthropologists conducted observation and key informant interviews to understand the human poultry interaction and poultry rearing practices. We collected swab samples and data from poultry (n=55) and humans (n=18). We tested all samples using specific real-time RT-PCR for influenza virus A (M gene), followed by subtype H5, H7, H9, and N2 and sequenced. Findings: We observed backyard poultry frequently scavenged inside and outside the kitchen and bedroom. The poultry farmers reported that children were involved in bird-raising activities and kept their chickens inside their living room at night. They handled sick poultry and slaughtered it without personal protective equipment. They rarely used soap after handing and slaughtering poultry and threw the poultry offal and entrails in the nearest water body or bushes. All human samples were negative against AIV. None of the poultry samples were positive for H5 and H7. H9N2 prevalence was 16.4% (n=9/55; 95%CI: 7.8-28.8) in bird level and 23.8% (n=5/21; 95%CI: 8.2-47.2) in farm level. Phylogenetic analysis of the H9N2 sequences suggests that these are like the previously circulated Bangladeshi G1-like lineage. Conclusion: The investigation revealed that H9N2 was circulating in the rural community and highlighted the significance of monitoring and characterizing AIV to understand the emergence of novel strains in poultry and the risk of spillover to humans. Human and poultry interaction with risky behavioral practices might facilitate transmitting the AIV from poultry to humans.