阿坝州3例人感染H7N9禽流感病例溯源调查分析

Traceability investigation and analysis of 3 cases human infection with avian influenza A(H7N9) virus in Aba Prefecture

目的探寻2017年4月27日—4月30日报告的3例阿坝州人感染H7N9禽流感病例的感染来源,为防控人感染H7N9禽流感提供科学依据。方法运用现场流行病学调查方法收集病例的临床和流行病学资料,采用RT-PCR方法检测病例及相关环境样本,分析病例流行病学特征及可能感染来源。结果 3例病例发病前10 d之内均有活禽市场接触史;病例之间无流行病学联系;病例的73名密切接触者10 d医学观察期内均未出现异常症状。3例病例接触的活禽市场、活禽来源中转站、中转站下游市场环境均检出H7N9阳性,外环境H7N9总阳性率达52.17%(12/23)。其中,笼具表面涂抹样本阳性率达6/12,环境综合涂抹样本阳性率6/9。结论本次疫情可能是由外地感染禽类进入我市禽类养殖批发中转站,通过鸡贩将受感染的禽类贩卖至省内的不同活禽交易市场,病例因暴露在活禽市场而感染致病。建议加强活禽交易市场规范管理,强化疫情源头控制,推行"规模养殖、集中屠宰、冷链运输、冰鲜上市"模式。

Objective To identify the possible infection source of 3 cases of human infection with avian influenza A(H7N9)virus in Aba prefecture reported from April 27,2017 to April 30,2017 and provide scientific evidence for the prevention and control of avian influenza A(H7N9)virus in human.Methods Clinical and epidemiological data of involved cases were collected by using the on-site epidemiological survey method.Case samples and related environmental samples were detected with RT-PCR.Epidemiological characteristics and possible sources of infection were analyzed.Results All of 3 cases had exposure history to live poultry markets within 10 days before onset.There were no epidemiological correlations among cases and no abnormal symptoms were found in 73 close contacts of 3 cases during the 10-day medical observation period.H7N9 positive samples were detected in live poultry markets which the patients exposed to,live poultry transfer station and its downstream markets.The total positive rate of H7N9 was 52.17%(12/23)among external environment.The positive rate of smear sample on surface of individual ventilated cages was 6/12,and the positive rate of environmental samples was 6/9.Conclusions Infected poultry from other places firstly enters local poultry breeding and wholesale transfer station,then is sold by chicken traders from transfer station to different live poultry markets within Sichuan Province,ultimately those cases exposed to live poultry markets are contaminated by H7N9.It is recommended to strengthen the standardized management of live poultry markets,enhance the control of infection sources,and implement the model of"scale farming,centralized slaughtering,cold chain transportation and chilled marketing".