Seroprevalence of Antibodies against Highly Pathogenic Avian Influenza A (H5N1) Virus among Poultry Workers in Bangladesh, 2009

We conducted a cross-sectional study in 2009 to determine the seroprevalence and risk factors for highly pathogenic avian influenza A (H5N1) [HPAI H5N1] virus antibodies among poultry workers at farms and live bird markets with confirmed/suspected poultry outbreaks during 2009 in Bangladesh. We tested sera by microneutralization assay using A/Bangladesh/207095/2008 (H5N1; clade 2.2.2) virus with confirmation by horse red blood cell hemagglutination inhibition and H5-specific Western blot assays. We enrolled 212 workers from 87 farms and 210 workers from three live bird markets. One hundred and two farm workers (48%) culled poultry. One hundred and ninety-three farm workers (91%) and 178 market workers (85%) reported direct contact with poultry that died during a laboratory confirmed HPAI H5N1 poultry farm outbreak or market poultry die-offs from suspected HPAI H5N1. Despite exposure to sick poultry, no farm or market poultry workers were seropositive for HPAI H5N1 virus antibodies (95% confidence interval 0–1%).本研究于2009年开展横断面研究（cross-sectional study），旨在明确孟加拉国2009年发生经确认或疑似家禽疫情的养殖场与活禽市场内，家禽从业人员的高致病性甲型禽流感H5N1（highly pathogenic avian influenza A (H5N1), HPAI H5N1）病毒抗体血清阳性率（seroprevalence）及其危险因素（risk factors）。本研究采用A/Bangladesh/207095/2008（H5N1；进化分支2.2.2）毒株开展微量中和试验（microneutralization assay），并通过马红细胞血凝抑制试验（horse red blood cell hemagglutination inhibition）及H5特异性免疫印迹试验（H5-specific Western blot assays）进行结果确认。本次研究共招募87家养殖场的212名从业人员，以及3家活禽市场的210名从业人员。其中102名养殖场从业人员（占比48%）参与过家禽扑杀工作。193名养殖场从业人员（占比91%）与178名市场从业人员（占比85%）报告称，曾直接接触过经实验室确认的HPAI H5N1养殖场疫情中死亡的家禽，或疑似HPAI H5N1疫情中死亡的市场家禽。尽管所有受试者均存在病禽接触暴露史，但未检测到任何养殖场或活禽市场从业人员的HPAI H5N1病毒抗体呈血清阳性，95%置信区间（confidence interval）为0~1%。