Amplification of avian influenza viruses along poultry marketing chains in Bangladesh: a controlled field experiment

The prevalence of avian influenza viruses (AIVs) is commonly found to increase dramatically from farms to live bird markets (LBMs). Viral transmission dynamics along marketing chains is, however, poorly understood. To address this gap, we implemented a field experiment altering chicken supply to an LBM in Chattogram, Bangladesh. Chickens traded along altered (intervention) and conventional (control) marketing chains were tested for AIVs. Upon arrival at the LBM, the odds of detecting AIVs did not differ between control and intervention groups. However, 12 hours later, intervention group odds were lower, particularly for broiler chickens, indicating that viral shedding in LBM resulted partly from infections during transport and trade. Curtailing AIV prevalence in LBMs requires mitigating risk in marketing chain nodes preceding chickens’ delivery at LBMs. Article Summary Line The high prevalence of avian influenza viruses in marketed chickens cannot be solely attributed to viral transmission within live bird markets but is also influenced by infections occurring prior to the chickens’ supply to these markets. ### Competing Interest Statement The authors have declared no competing interest.