2017年北京市大兴区首例人感染H7N9禽流感病例感染来源分析

目的对2017年北京市大兴区首例人感染H7N9禽流感确诊病例的感染来源及部分基因序列进行分析，为人感染H7N9禽流感疫情防控提供依据。方法采用现场流行病学调查和实验室检测相结合的方法，追溯病例的感染来源。结果病例发病前1周有活禽接触史，病例咽拭子、深咳痰液、血液标本人感染H7N9禽流感核酸均为阳性，在暴露的活禽及外环境中检出H7N9禽流感病毒核酸阳性，7名共同暴露者及密切接触者核酸检测为阴性。 血凝素（HA）基因和神经氨酸酶（NA）基因测序分析显示未发生明显变异。结论活禽暴露是该病例感染的关键风险因素，病例的感染来源是购自某流动集市的活禽，病毒基因测序及HA0裂解位点测定，该病毒属于禽H7N9长江三角洲分支病毒，为低致病性禽流感病毒。

Infection source of the first case of human infection with avian influenza A (H7N9) virus in Daxing district of Beijing, 2017

ObjectiveTo understand the infection source of the first case of human infection with avian influenza A (H7N9) virus in Daxing district of Beijing in 2017, and provide scientific evidence for the prevention and control of human H7N9 virus infection.MethodsField epidemiological investigation and laboratory testing method were used to trace the possible source of infection.ResultsThe exposure to live poultry of the case occurred one week before the onset of the disease. Throat swabs, deep cough sputum fluid, and serum samples of case were nucleic acid positive for H7N9 virus. H7N9 virus nucleic acid was detected in both live poultry and its environment. Seven other exposed individuals and close contacts were found to be nucleic acid negative. Sequencing analysis of hemagglutinin (HA) gene and neuraminidase (NA) gene showed no significant variation.ConclusionLive poultry exposure history was one of key risk factors of H7N9 virus infection. The source of infection was live poultry purchased from a floating market. The sequencing of the virus and the HA0 cleavage site of the virus indicated that the virus belongs to the virus of H7N9 Yangtze River Delta branch and is a low-pathogenic avian influenza virus.