Nature聚焦：H1N1三大特征（图）

　　

生物通报道，最新的Nature新闻报道了来自美国关于H1N1的最新研究进展，这份新的研究报告称，对H1N1病毒的研究分析发现年轻人对新型流感病毒更易感。研究人员整理出目前H1N1的最新三大特征。

 

生物通整理，截至5月11日，全球甲型H1N1流感确诊病例继续大幅度增加，目前，，美国的确诊病例人数已经超过墨西哥，成为确诊病例最多的国家。美国的科学家从目前的642例患者身上分离到的H1N1，经过研究分析找出新型H1N1的临床特征，易感人群特征，和传播特征。

 

执行这一研究的是美国亚特兰大疾控中心（Centers for Disease Control and Prevention，CDC）的研究人员，从4月15日起，这一新型的流感病毒穿越41个州，走遍美国。在纽约城，有80个确诊病例，成为发病率第二高的城市，而在哥伦比亚特区却没有发现确诊病例。

 

 

这些研究成果公布在权威期刊New England Journal of Medicine上，领导该研究的是美国CDC的流行病学专家Fatimah Dawood。

 

特征一  年轻人更易感

据介绍，目前感染H1N1的大部分（60%）患者年龄在18岁左右，只有5%的患者年龄超过50岁。这表明，儿童和年轻人更易感染H1N1新型病毒，也即是该新型毒株在老年人中的传播速度变缓。

 

特征二  临床特征类似季节性流感 偶见腹泻，呕吐

临床数据显示，大部分的患者表现的临床症状为发热，咳嗽，这些症状与季节性流感类似。还有其他出现率不高的症状，如腹泻和呕吐，不过这些症状只偶尔发生。

 

特征三 传播途径尚不明确

尽管目前的研究还没有确认H1N1的传播路径。由于有些患者出现腹泻的症状，因此有学者怀疑H1N1可能经排泄物传播，这有待进一步证实。目前普遍认为的传播方式是，飞沫传播，通过喷嚏，咳嗽传播。

 

H1N1在美分布图

 

研究人员称，除非有充足的证据证实某一传播途径是有效的传播途径，目前，每一种传播途径都被认可。

 

热点评论

英国国立医学研究所病毒学家John McCauley称，新型流感的易感年龄群的研究十分具有意义，如果说50岁以上的人对新型流感不易感，且症状温和，这可能在释放一个信息，这些50岁以上的人群可能对猪流感病毒具有抵抗力。

（生物通 小茜）

 

参考文献

Novel Swine-Origin Influenza A (H1N1) Virus Investigation Team N. Engl. J. Med. doi:10.1056/NEJMoa0903810 (2009).

The members of the writing group (Fatimah S. Dawood, M.D., Epidemic Intelligence Service, Office of Workforce and Career Development; and Seema Jain, M.D., Lyn Finelli, Dr.P.H., Michael W. Shaw, Ph.D., Stephen Lindstrom, Ph.D., Rebecca J. Garten, Ph.D., Larisa V. Gubareva, M.D., Ph.D., Xiyan Xu, M.D., Carolyn B. Bridges, M.D., and Timothy M. Uyeki, M.D., M.P.H, M.P.P., Influenza Division, National Center for Immunization and Respiratory Diseases - all at the Centers for Disease Control and Prevention, Atlanta) assume responsibility for the overall content and integrity of the article. This article (10.1056/NEJMoa0903810) was published at NEJM.org on May 7, 2009. It will appear in the July 2 issue of the Journal.

【Abstract】

BACKGROUND: On April 15 and April 17, 2009, novel swine-origin influenza A (H1N1) virus (S-OIV) was identified in specimens obtained from two epidemiologically unlinked patients in the United States. The same strain of the virus was identified in Mexico, Canada, and elsewhere. We describe 642 confirmed cases of human S-OIV infection identified from the rapidly evolving U.S. outbreak. METHODS: Enhanced surveillance was implemented in the United States for human infection with influenza A viruses that could not be subtyped. Specimens were sent to the Centers for Disease Control and Prevention for real-time reverse-transcriptase-polymerase-chain-reaction confirmatory testing for S-OIV. RESULTS: From April 15 through May 5, a total of 642 confirmed cases of S-OIV infection were identified in 41 states. The ages of patients ranged from 3 months to 81 years; 60% of patients were 18 years of age or younger. Of patients with available data, 18% had recently traveled to Mexico, and 16% were identified from school outbreaks of S-OIV infection. The most common presenting symptoms were fever (94% of patients), cough (92%), and sore throat (66%); 25% of patients had diarrhea, and 25% had vomiting. Of the 399 patients for whom hospitalization status was known, 36 (9%) required hospitalization. Of 22 hospitalized patients with available data, 12 had characteristics that conferred an increased risk of severe seasonal influenza, 11 had pneumonia, 8 required admission to an intensive care unit, 4 had respiratory failure, and 2 died. The S-OIV was determined to have a unique genome composition that had not been identified previously. CONCLUSIONS: A novel swine-origin influenza A virus was identified as the cause of outbreaks of febrile respiratory infection ranging from self-limited to severe illness. It is likely that the number of confirmed cases underestimates the number of cases that have occurred. Copyright 2009 Massachusetts Medical Society.