宁波市2012年麻疹病毒流行病学和生物学特征

Biological and epidemiological characteristics of measles virus in Ningbo in 2012

目的2012年宁波市麻疹野毒株流行病学和分子生物学特征。方法对2012年宁波麻疹发病情况进行描述流行病学分析；并对麻疹野毒株核蛋白基因碳末端450个核苷酸进行扩增，测序后与基因库中麻疹病毒各基因型参考株作比对分析。结果麻疹发病季节主要集中在3月-6月。宁波市发病率居前3位的是鄞州区（10．46／10万）、江东区（10．36／10万）和海曙区（9．36／10万）。宁波市麻疹的高发年龄呈小年龄儿童和成年人，发病病人中〈8月龄占病例总数的30．60％（127／415）；≥15周岁占病例总数的55．66％（231／415）。宁波市分离的2株麻疹野毒株为H1a基因亚型，与2008年宁波分离株同源性为97．8％-98．2％，与Hla亚型参考株china93—4的同源性为98．7％-98．9％，与Hlb亚型参考株china94—7的同源性为96．7％-96．9％，与中国疫苗株S191同源性为92．0％～92．2％。结论麻疹常规免疫接种率和首针及时接种率不高，是宁波市麻疹高发的主要原因。2012年宁波分离的麻疹毒株主要为H1a亚型。

Objective To study the epidemiologieal and molecular biological characteristics of wild - type measles virus strains in Ningho in 2012. Methods Descriptive epidemiological analysis was conducted to analyze the incidence of measles in Ning- bo. While 450bp fragments of C terminus of wile type measles virus nucleoprotein （N） gene were amplified by RT- PCR, then sequenced and compared with other measles virus strains published in GeneBank. Results Epidemic season mainly concentrat- ed from March to June. The high incidence was mainly found in economically advanced areas, Yinzhou district, Jiangdong dis- trict and Haishu district ranked the top three, with the average annual incidence of 10.46 / lakh, 10.36/lakh, 9.36/lakh, respectively. In all the measles eases, the proportion of infants less than 8 months was 30.60% （127/415） , while that of per- son more than 15 years old was 55.66% （231/415）. The two wild type measles virus isolates both belonged to Hla subtype, when compared to the H1 a subtype reference strain China 93 -4, H1 b subtype reference strain China 94 -7, China vaccine strain S191 and Ningno isolates in 2008, the homology were 98.7% - 98.9%, 96.7% - 96.9%, 92.0% - 92.2% and 97.8% - 98.2%, respectively. Conclusion Low coverage of measles vaccination was the main cause of high measles inci- dence in Ningbo. The predominant epidemic strains were Hla subtype in Ningbo in 2012.