New England Journal of Medicine
November 21, 2013  Vol. 369 No. 21
http://www.nejm.org/toc/nejm/medical-journal

Original Article
Identification and Control of a Poliomyelitis Outbreak in Xinjiang, China
Hui-Ming Luo, M.D., Yong Zhang, M.D., Ph.D., Xin-Qi Wang, M.D., Wen-Zhou Yu, M.D., Ph.D., M.P.H., Ning Wen, M.Sc., Dong-Mei Yan, M.Sc., Hua-Qing Wang, M.D., Ph.D., Fuerhati Wushouer, M.D., Hai-Bo Wang, M.D., Ph.D., Ai-Qiang Xu, M.D., Jing-Shan Zheng, M.D., De-Xin Li, M.D., Hui Cui, B.Sc., Jian-Ping Wang, M.Sc., Shuang-Li Zhu, B.Sc., Zi-Jian Feng, M.D., Fu-Qiang Cui, M.D., Ph.D., M.P.H., Jing Ning, B.Sc., Li-Xin Hao, M.D., Ph.D., Chun-Xiang Fan, M.Sc., Gui-Jun Ning, M.Sc., Hong-Jie Yu, M.D., Shi-Wen Wang, M.D., Ph.D., Da-Wei Liu, M.D., Dong-Yan Wang, B.Sc., Jian-Ping Fu, M.D., Ai-li Gou, B.Sc., Guo-Min Zhang, Ph.D., Guo-Hong Huang, B.Sc., Yuan-Sheng Chen, M.D., Ph.D., Sha-Sha Mi, M.D., Yan-Min Liu, M.D., Da-Peng Yin, Ph.D., Hui Zhu, B.Sc., Xin-Chun Fan, B.Sc., Xin-Lan Li, B.Sc., Yi-Xin Ji, M.Sc., Ke-Li Li, M.D., Hai-Shu Tang, M.Sc., Wen-Bo Xu, M.D., Yu Wang, M.D., Ph.D., M.P.H, and Wei-Zhong Yang, M.D.
N Engl J Med 2013; 369:1981-1990November 21, 2013DOI: 10.1056/NEJMoa1303368

Background
The last case of infection with wild-type poliovirus indigenous to China was reported in 1994, and China was certified as a poliomyelitis-free region in 2000. In 2011, an outbreak of infection with imported wild-type poliovirus occurred in the province of Xinjiang.
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Methods
We conducted an investigation to guide the response to the outbreak, performed sequence analysis of the poliovirus type 1 capsid protein VP1 to determine the source, and carried out serologic and coverage surveys to assess the risk of viral propagation. Surveillance for acute flaccid paralysis was intensified to enhance case ascertainment.
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Results
Between July 3 and October 9, 2011, investigators identified 21 cases of infection with wild-type poliovirus and 23 clinically compatible cases in southern Xinjiang. Wild-type poliovirus type 1 was isolated from 14 of 673 contacts of patients with acute flaccid paralysis (2.1%) and from 13 of 491 healthy persons who were not in contact with affected persons (2.6%). Sequence analysis implicated an imported wild-type poliovirus that originated in Pakistan as the cause of the outbreak. A public health emergency was declared in Xinjiang after the outbreak was confirmed. Surveillance for acute flaccid paralysis was enhanced, with daily reporting from all public and private hospitals. Five rounds of vaccination with live, attenuated oral poliovirus vaccine (OPV) were conducted among children and adults, and 43 million doses of OPV were administered. Trivalent OPV was used in three rounds, and monovalent OPV type 1 was used in two rounds. The outbreak was stopped 1.5 months after laboratory confirmation of the index case.
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Conclusions
The 2011 outbreak in China showed that poliomyelitis-free countries remain at risk for outbreaks while the poliovirus circulates anywhere in the world. Global eradication of poliomyelitis will benefit all countries, even those that are currently free of poliomyelitis.