SPATIAL AND TEMPORAL DISTRIBUTION PATTERN OF AVIAN INFLUENZA IN LIVE BIRD MARKETS NEAR MIGRATORY AND NON-MIGRATORY BIRD POPULATIONS IN BANGLADESH

Abstract

Avian Influenza viruses (AIVs) type A infect poultry birds, usually more common in wild waterfowl. Avian Influenza (AI) is a vital threat to the economy, public health, and food security of a country with large poultry industries like Bangladesh. The live bird market (LBM) is usually an interaction hub for poultry traders and consumers in terms of live bird trading. To date, H5 and H9 are the most common subtypes detected in live bird markets (LBMs) in poultry. This study aims to assess whether proximity to migratory sites influences the prevalence of AIV in poultry birds, particularly for the H5 subtype. From December 2022 to July 2023, a repeated cross-sectional study was conducted in peri-rural and urban areas of Bangladesh. We aimed to investigate the distribution pattern of AIVs in LBMs. Poultry production distributions and eBird (an electronic bird observation database developed by the Cornell Lab of Ornithology) prediction modelling were used to select peri-rural areas with high and low interaction between migratory birds and domestic poultry. A total of 7401 oropharyngeal and cloacal swabs from 5415 individual birds, such as exotic broilers, sonali, ducks, and deshi chickens, were collected from LBMs. The samples then underwent Real-time Reverse Transcriptase Polymerase Chain Reaction (rRT-PCR) for detection of the M gene, followed by H5 and H9 subtypes. The study found a higher AIV infection rate in LBMs with multiple wholesalers than in retail-only LBMs. The prevalence of A (H5) virus was higher in ducks, 29.7% (95% CI: 27.5-31.9). On the other hand, the H9 was more prevalent in chickens, notably in sonali 34.4% (95% CI: 31.6-37.1) compared to broiler 29.3% (95% CI: 26.7-31.8) and native deshi chickens 17.6% (95% CI: 15.2-19.9). Oropharyngeal swabs showed a higher prevalence for H9 subtype 27.4% (95% CI: 26-28.8), whereas cloacal swabs expressed comparatively high prevalence for H5 subtype 6.2% (95% CI: 4.9-7.5). In high human density areas, LBMs had higher prevalence for both H5 20.9% (95% CI: 18.8-22.9) and H9 27.9% (95% CI: 25.6-30.2) subtypes than in high and low migratory bird density areas. Furthermore, no clear seasonal pattern is noticed in AIV prevalence. This suggests that there may be no or less pronounced connection between AIV prevalence and migratory bird populations. The study findings lead to a deeper understanding of the role of wild-domestic bird interactions in shaping the prevalence and diversity of AIV within existing poultry trading networks in Bangladesh. This understanding can guide the implementation of adequate measures to mitigate the risk of AIV outbreaks in the country.