Division of Epidemiology, Dalla Lana School of Public Health, University of Toronto, Toronto, Canada.
Zhejiang Provincial Center for Disease Prevention &Control, Hangzhou, P.R. China.
Sci Rep. 2017 Jan 5;7:40016. doi: 10.1038/srep40016.
Inapparent avian exposure was suspected for the sporadic infection of avian influenza A(H7N9) occurring in China. This type of exposure is usually unnoticed and difficult to model and measure. Infected poultry with avian influenza H7N9 virus typically remains asymptomatic, which may facilitate infection through inapparent poultry/bird exposure, especially in a country with widespread practice of backyard poultry. The present study proposed a novel approach that integrated ecological and case-control methods to quantify the risk of inapparent avian exposure on human H7N9 infection. Significant associations of the infection with chicken and goose densities, but not with duck density, were identified after adjusting for spatial clustering effects of the H7N9 cases across multiple geographic scales of neighborhood, community, district and city levels. These exposure risks varied geographically in association with proximity to rivers and lakes that were also proxies for inapparent exposure to avian-related environment. Males, elderly people, and farmers were high-risk subgroups for the virus infection. These findings enable health officials to target educational programs and awareness training in specific locations to reduce the risks of inapparent exposure.
疑似禽源性暴露被怀疑是中国偶发的人感染甲型流感 H7N9 病毒的原因。这种暴露通常是未被注意到的，难以建模和测量。感染 H7N9 病毒的禽类通常没有症状，这可能通过隐性禽类/鸟类暴露而促进感染，特别是在一个广泛存在后院禽类养殖的国家。本研究提出了一种新方法，将生态和病例对照方法相结合，以量化隐性禽源暴露对人感染 H7N9 的风险。在调整了 H7N9 病例在多个地理尺度（邻里、社区、区和市级）上的空间聚类效应后，发现感染与鸡和鹅的密度显著相关，但与鸭的密度无关。这些暴露风险与河流和湖泊的接近程度有关，这些河流和湖泊也是隐性接触与禽类相关环境的代表，具有地理差异。男性、老年人和农民是该病毒感染的高风险亚组。这些发现使卫生官员能够在特定地点开展教育计划和意识培训，以降低隐性暴露的风险。
