Liang Xiaofeng, Zhang Yong, Xu Wenbo, Wen Ning, Zuo Shuyan, Lee Lisa A, Yu Jingjin
National Immunization Programme, China Center for Disease Control and Prevention, Beijing, People's Republic of China, 100044.
J Infect Dis. 2006 Sep 1;194(5):545-51. doi: 10.1086/506359. Epub 2006 Jul 26.
In May-July 2004, type 1 vaccine-derived poliovirus (VDPV) was isolated from 2 case patients with polio and a contact of a third case patient in Guizhou Province.
We conducted a field investigation of the outbreak, characterized outbreak isolates, and retrospectively reviewed national polio surveillance data for other VDPVs.
Case patients were unimmunized children, 0.9-3.2 years old, living in 2 villages 40 km apart. Immunization coverage in the affected villages was very low. Isolates differed from the Sabin 1 type by 9-11 VP1 nucleotides (1.0%-1.2%); which indicated, on the basis of known rates of mutation of Sabin strains, that they had been circulating for <1 year. A province-wide immunization response targeting all children <5 years old was initiated in August, and the strain has not been isolated since. During 1997-2004, 10 VDPV strains (5 of type 2, 3 of type 1, and 2 of type 3) were isolated from >50,000 children with acute flaccid paralysis and their contacts; 8 (80%) were found in southern provinces, and 9 (90%) spontaneously disappeared.
This is the first polio outbreak in China in over a decade and the first due to VDPV. The short duration of circulation demonstrates the rapidity with which attenuated Sabin strains can revert to a wild phenotype. One to two VDPVs have been identified each year, primarily in densely populated subtropical regions of southern China. This outbreak highlights the need to consider risks of paralysis from vaccine-derived strains in development of national poliomyelitis immunization policy.
2004年5月至7月，在贵州省从2例脊髓灰质炎病例患者以及第3例病例患者的1名接触者中分离出1型疫苗衍生脊髓灰质炎病毒（VDPV）。
我们对此次疫情进行了现场调查，对疫情分离株进行了特征分析，并回顾性审查了其他VDPV的国家脊髓灰质炎监测数据。
病例患者为未接种疫苗的儿童，年龄在0.9至3.2岁之间，居住在相距40公里的2个村庄。受影响村庄的免疫接种覆盖率非常低。分离株与Sabin 1型在9至11个VP1核苷酸上存在差异（1.0%至1.2%）；根据Sabin株已知的突变率，这表明它们的传播时间<1年。8月启动了针对所有5岁以下儿童的全省免疫应对措施，此后未再分离出该毒株。1997年至2004年期间，从50000多名急性弛缓性麻痹儿童及其接触者中分离出10株VDPV毒株（2型5株、1型3株、3型2株）；8株（80%）在南部省份发现，9株（90%）自行消失。
这是中国十多年来首次脊髓灰质炎疫情，也是首次由VDPV引起的疫情。病毒传播持续时间短表明减毒Sabin株可迅速恢复为野生表型。每年识别出1至2株VDPV，主要在中国南部人口密集的亚热带地区。此次疫情凸显了在制定国家脊髓灰质炎免疫政策时需要考虑疫苗衍生毒株导致麻痹的风险。
