CIRCULATION OF AVIAN INFLUENZA H5N1 AND H9N2 VIRUS IN DHAMRAI AND SAVAR UPAZILA, BANGLADESH

Abstract

Intro: In January 2017, a highly pathogenic avian influenza (HPAI) H5N1 outbreak was reported at a chicken farm in Dhamrai, Bangladesh. Subsequently, we investigated outbreak settings to determine the extent of the outbreak and whether HPAI has been circulating in the live bird market (LBM) and among wild birds and to identify possible associated risk factors of infection. Methods: We surveyed nearly all LBMs (N=45) in outbreak areas. We collected oropharyngeal swab samples from dead crows (N=3) and environmental pool samples from LBMs (N=116). We tested the swabs using real-time RT-PCR for Mgene and followed HA and NA subtyped and sequenced. We conducted a univariable analysis and then generalized linear mixed model (GLMM) to identify the associated risk factors of AIV contamination at LBMs. Findings: The team observed house crows feeding on poultry wastage in neighboring LBMs, and results expressed that, in crows, 100% (n=3; 95%CI: 29-100) were positive for A/H5N1. Of the 116 environmental samples, 36% (n=42; 95% CI: 27.5-45.6) were positive for AIV, including: A/H5 4.3% (n=5; 95% CI: 1.4-9.7), A/H9 6% (n=7; 95% CI: 2.5-12.1), 1% A/H5/H9 co-infection (n=1; 95%CI: 0.02-4.7) and A/untyped 25% (n=29; 95% CI: 17.4-33.9). In the multivariable model, we identified multiple poultry species, improper disposal of offal, slaughtering of poultry, and access of wild birds were associated with AIV contamination at the shop level. Phylogenetic analysis based on HA and NA genes suggests H5N1 in the crows and LBM is similar to the Bangladeshi 2.3.2.1a clade that circulated in 2011. Conclusion: The investigation suggests multiple AIV subtypes circulating in LBMs and crows. Outbreak settings serve as an effective tool to detect major AIVs that pose a public health risk and lay a foundation for both veterinary and public health officials if one or more of these viruses causes outbreaks or significant disease in birds or humans.