Biosecurity and Circulation of Influenza A (H5N1) Virus in Live-Bird Markets in Bangladesh, 2012

Bangladesh has been considered as one of the five countries endemic with highly pathogenic avian influenza A subtype H5N1 (HPAI H5N1). Live-bird markets (LBMs) in south Asian countries are believed to play important roles in the transmission of HPAI H5N1 and others due to its central location as a hub of the poultry trading. Food and Agriculture Organization (FAO) of the United Nations has been promoting improved biosecurity in LBMs in Bangladesh. In 2012, by enrolling 32 large LBMs: 10 with FAO interventions and 22 without assistance, we assessed the virus circulation in the selected LBMs by applying standard procedures to investigate market floors, poultry stall floors, poultry-holding cases and slaughter areas and the overall biosecurity using a questionnaire-based survey. Relative risk (RR) was examined to compare the prevalence of HPAI H5N1 in the intervened and non-intervened LBMs. The measures practised in significantly more of the FAO-intervened LBMs included keeping of slaughter remnants in a closed container; decontamination of poultry vehicles at market place; prevention of crows' access to LBM, market/floor cleaning by market committee; wet cleaning; disinfection of floor/poultry stall after cleaning; and good supply of clean water at market (P<0.05). Conversely, disposal of slaughter remnants elsewhere at market and dry cleaning were in operation in more of the FAO non-intervened LBMs (P<0.05). The RR for HPAI H5N1 in the intervened and non-intervened LBMs was 1.1 (95% confidence interval 0.44-2.76), suggesting that the proportion positive of the virus in the two kinds of LBM did not vary significantly (P=0.413). These observations suggest that the viruses are still maintained at the level of production in farms and circulating in LBMs in Bangladesh regardless of interventions, albeit at lower levels than in other endemic countries.