The authors' affiliations are listed in the Appendix.
N Engl J Med. 2014 Feb 6;370(6):520-32. doi: 10.1056/NEJMoa1304617. Epub 2013 Apr 24.
The first identified cases of avian influenza A(H7N9) virus infection in humans occurred in China during February and March 2013. We analyzed data obtained from field investigations to describe the epidemiologic characteristics of H7N9 cases in China identified as of December 1, 2013.
Field investigations were conducted for each confirmed case of H7N9 virus infection. A patient was considered to have a confirmed case if the presence of the H7N9 virus was verified by means of real-time reverse-transcriptase-polymerase-chain-reaction assay (RT-PCR), viral isolation, or serologic testing. Information on demographic characteristics, exposure history, and illness timelines was obtained from patients with confirmed cases. Close contacts were monitored for 7 days for symptoms of illness. Throat swabs were obtained from contacts in whom symptoms developed and were tested for the presence of the H7N9 virus by means of real-time RT-PCR.
Among 139 persons with confirmed H7N9 virus infection, the median age was 61 years (range, 2 to 91), 71% were male, and 73% were urban residents. Confirmed cases occurred in 12 areas of China. Nine persons were poultry workers, and of 131 persons with available data, 82% had a history of exposure to live animals, including chickens (82%). A total of 137 persons (99%) were hospitalized, 125 (90%) had pneumonia or respiratory failure, and 65 of 103 with available data (63%) were admitted to an intensive care unit. A total of 47 persons (34%) died in the hospital after a median duration of illness of 21 days, 88 were discharged from the hospital, and 2 remain hospitalized in critical condition; 2 patients were not admitted to a hospital. In four family clusters, human-to-human transmission of H7N9 virus could not be ruled out. Excluding secondary cases in clusters, 2675 close contacts of case patients completed the monitoring period; respiratory symptoms developed in 28 of them (1%); all tested negative for H7N9 virus.
Most persons with confirmed H7N9 virus infection had severe lower respiratory tract illness, were epidemiologically unrelated, and had a history of recent exposure to poultry. However, limited, nonsustained human-to-human H7N9 virus transmission could not be ruled out in four families.
2013 年 2 月至 3 月期间，中国首次发现人感染甲型禽流感病毒（H7N9）病例。我们分析了截至 2013 年 12 月 1 日获得的现场调查数据，以描述中国 H7N9 病例的流行病学特征。
对每例确诊的 H7N9 病毒感染病例进行现场调查。通过实时逆转录聚合酶链反应（RT-PCR）检测、病毒分离或血清学检测证实 H7N9 病毒存在的患者被视为确诊病例。从确诊病例患者中获取人口统计学特征、暴露史和疾病时间线信息。对密切接触者进行为期 7 天的疾病症状监测。对出现症状的接触者采集咽拭子，并通过实时 RT-PCR 检测 H7N9 病毒的存在。
在 139 名确诊的 H7N9 病毒感染患者中，中位年龄为 61 岁（范围，2 岁至 91 岁），71%为男性，73%为城市居民。确诊病例发生在中国 12 个地区。9 人是家禽工人，在可获得数据的 131 人中，82%有接触活禽的病史，包括鸡（82%）。共有 137 人（99%）住院，125 人（90%）患有肺炎或呼吸衰竭，65 人（103 人中有可获得数据的人）（63%）住进重症监护病房。共有 47 人（34%）在中位发病 21 天后死于医院，88 人出院，2 人仍住院病危；2 名患者未入院。在 4 个家庭聚集性病例中，不能排除 H7N9 病毒的人际传播。排除聚集性病例中的继发性病例后，2675 名病例患者的密切接触者完成了监测期；其中 28 人（1%）出现呼吸道症状；所有呼吸道症状患者的 H7N9 病毒检测均为阴性。
大多数确诊的 H7N9 病毒感染患者均患有严重的下呼吸道疾病，与禽类无流行病学关联，且近期有接触禽类的病史。然而，在 4 个家庭中，不能排除有限的、不持续的人际 H7N9 病毒传播。
