Department of Environmental and Global Health, College of Public Health and Health Professions Emerging Pathogens Institute, University of Florida, Gainesville.
Department of Environmental and Global Health, College of Public Health and Health Professions Emerging Pathogens Institute, University of Florida, Gainesville Division of Infectious Diseases, Global Health Institute, & Nicholas School of the Environment, Duke University, Durham, North Carolina Laboratory of One Health Research, Program in Emerging Infectious Diseases, Duke-NUS Graduate Medical School, Singapore.
J Infect Dis. 2015 Aug 15;212(4):562-9. doi: 10.1093/infdis/jiv109. Epub 2015 Feb 23.
Given that influenza A(H9N2) is recognized as a pandemic threat, we evaluated the overall burden of influenza A(H9N2) infections among avian-exposed human populations.
We performed a systematic search of PubMed, AGRICOLA, and CAB Abstracts databases for literature published during 1997-2013. Studies reporting serological evidence of human influenza A(H9N2) infection among avian-exposed populations were included. We used a World Health Organization (WHO)-recommended case definition for serological evidence of infection based on results of hemagglutination inhibition (HI) and microneutralization (MN) assays. We calculated overall seroprevalence through a random effects meta-analysis model.
Seroprevalence data reported by the studies ranged from 1% to 43% (median, 9%) by HI, which was not significantly different from the seroprevalence estimated through the WHO-recommended case definition (median, 1.3%; range, 0.5%-42.6%). Reported seroprevalence by MN ranged from 0.6% to 9% (median, 2.7%), which was greater than the seroprevalence estimated through the WHO-recommended case definition (median, 0.3%; range, 0.1%-1.4%).
A small proportion of avian-exposed humans had evidence of influenza A(H9N2) infection. As the virus has a near global distribution in poultry, it seems likely that present surveillance efforts are missing mild or asymptomatic infections among avian-exposed persons. It seems prudent to closely monitor avian-exposed populations for influenza A(H9N2) infection to provide prepandemic warnings.
鉴于甲型 H9N2 流感已被确认为一种大流行威胁，我们评估了禽类接触人群中甲型 H9N2 流感感染的总体负担。
我们对 1997 年至 2013 年期间发表的文献，在 PubMed、AGRICOLA 和 CAB Abstracts 数据库中进行了系统检索。纳入了报道禽类接触人群中存在甲型 H9N2 流感血清学证据的研究。我们使用世界卫生组织（WHO）推荐的血清学感染病例定义，根据血凝抑制（HI）和微量中和（MN）检测结果进行判断。我们使用随机效应荟萃分析模型计算了总体血清阳性率。
研究报告的 HI 血清阳性率范围为 1%至 43%（中位数，9%），与 WHO 推荐的病例定义估计的血清阳性率（中位数，1.3%；范围，0.5%-42.6%）无显著差异。MN 报告的血清阳性率范围为 0.6%至 9%（中位数，2.7%），高于 WHO 推荐的病例定义估计的血清阳性率（中位数，0.3%；范围，0.1%-1.4%）。
少数禽类接触者有甲型 H9N2 流感感染的证据。由于该病毒在禽类中几乎全球分布，目前的监测工作似乎很可能漏掉了禽类接触者中的轻症或无症状感染。对禽类接触者进行密切监测，以提供大流行前预警，似乎是谨慎的做法。
