江西上饶一起人感染H7N9禽流感家庭聚集性疫情调查

Family clustering of human infection with avian influenza A(H7N9) virus:a case investigation in Shangrao city,Jiangxi province

目的分析江西省一起人感染H7N9禽流感家庭聚集性疫情的流行病学特征,分析病例的感染来源,并探讨其传播模式。方法应用现场流行病学方法调查2例病例及其57名密切接触者,采用real-time RT-PCR对采集的相关标本进行H7N9禽流感病毒核酸检测并分析病例病毒基因序列。结果 2例H7N9禽流感确诊病例为母女关系,均因抢救无效死亡。2例病例发病前有禽类暴露史,居住地外环境标本检测出H7N9禽流感病毒。病毒基因进化分析结果显示,病例H7N9病毒仍属于长三角分支,对禽类低致病性。病例1的密切接触者中,除病例2于2月4日发病外,其余密切接触者经医学观察未出现异常。结论本起家庭聚集性疫情中,病例1的感染来源可能为被H7N9禽流感病毒污染的环境,病例2的感染途径为共同暴露还是有限的人传人尚无明确证据。

Objective To investigate the epidemic characteristics of a family clustering of human infection with avian influenza A （H7N9） virus in Jiangxi province and to analyze the source and transmission mode of the infection.Methods Two patients and their 57 close contacts were surveyed with a field investigation. The specimens sampled from the patients, close contacts and environment were tested by using real time reverse transcriptase-polymerase chain reaction （RT-PCR） and gene sequencing.Results A 40 months old girls （the first case） and her 22 years old mother from Shangrao city of Jiangxi province were confirmed as avian influenza A （H7N9） virus infection on February 9 and 10, 2017. Both of the cases had a history of exposure to poultry before the incidence of the infection and the specimens collected from their residential environment were positive for avian influenza A （H7N9） virus. The phylogenetic tree analysis showed that the H7N9 virus strain isolated from the patients belonge to the Yangtze River Delta Lineage and is of low pathogenicity to birds. No abnormalities were observed during medical observation among all the close contacts of the girl patient, except for her mother with clinical symptoms 5 days after the occurrence of the girl＇s disease.Conclusion The incidence of human avian influenza （H7N9） virus infection is a family clustering epidemic; the infection source for the first case could be the environment contaminated by the virus but there is no clear evidence for confirming the secondary infection being due to co-exposure to contaminated environment or limited human to human infection.