广州地区儿童A族链球菌流行趋势连续7年调查

目的 探讨广州地区学龄儿童A族链球菌(GAS)流行特点和流行趋势.方法 1988年9月-1994年8月连续7年,以及2005年10月,用整群随机抽样方法,在广州地区城乡选择8～13岁的学龄儿童共1 907人,其中市区和农村地区每年各约200人,男女大致各半.每月做1次咽拭了血平板GAS培养(共17 819人次),阳性菌株进行T分型和OF分型;每3个月抽血1次(共5 854人次),用微量法测定血清抗DNA酶B抗体水平.结果 ①GAS年均带菌率:农村为18.2%,明显高于城市14.6%(χ2=43.547,P0＜0.001);GAS年均感染率:农村为34.1%,城市为32.1%(χ2=2.647,P＞0.05);城乡带菌率及感染率均以秋、冬、春季较高,夏季较低.②研究期内,GAS带菌率和感染率农村呈下降趋势,城市则略呈缓慢上升趋势;1992年以前农村GAS带菌率和感染率均明显高于城市(P＜0.01),1992年后农村GAS带菌率和感染率均低于城市,除1993-1994年度带菌率差异无统计学意义外,其他年度差异均有统计学意义.③GAS阳性儿童中,只有6.9%有典型症状,10.7%症状不典型,82.4%无症状.④1年内有近50%的儿童曾携带GAS,同一个体1年多次(月)带菌现象非常普遍,约35%的儿童带菌2次以上,26%带菌3次以上,有的连续12个月带菌.⑤研究期内,学龄儿童咽部流行的GAS的主导菌株依次为T6、4、1、11、8/25/1MP19和5/25/44,城乡两地流行的主导菌型差异较大,不同年份GAS T型分布差异也有统计学意义.结论 广州地区儿童GAS的流行很普遍,及时诊断和合理治疗GAS咽炎患儿、加强医疗卫生保健、改善居住环境是预防风湿热流行的关键.

A 7-year epidemiologic study of group A streptococcus among school-age children in Guangzhou

Objectives To investigate the epidemiologic features of infections with group A streptococci(GAS) among school-age children in Guangzhou. Methods From September 1988 to August 1994,and in October 2005,total 1907 school-age children were selected by cluster randomized method,about 200 school-age children(49% were male)per year from Guangzhou countryside and city respectively. The mean age was 10.7 years(range 8-13 years). During the investigation period,throat swab cultures for GAS(17 819 throat cultures)were taken monthly,and serum anti-DNAse B titers(5854 serum anti-DNAse B titers)were determined every three months for each participant. Results (1)The annual incidence of GAS throat carrier was higher in countryside than that in city,18.2% in countryside and 14.6% in city. The annual incidence of GAS throat infection was 34.1% in countryside and 32.1% in city. Both of the incidences of GAS throat carrier and GAS throat infection were higher in autumn,winter and spring,when compared with that in summer. (2)During the investigation period,both of the incidences of GAS throat carrier and GAS throat infection had showed a marked downtrend in countryside,while there was a slow uptrend in city. Before 1992,both of the incidences of GAS throat carrier and GAS throat infection were higher in countryside than that in city. However,after 1992,they were lower in countryside than that in city,except in 1993 -1994,when there were no significant difference between that in countryside and city. (3)Among the children whose GAS culture was positive,only 6.9% of them had typical symptoms, 10.7% had atypical symptoms,and more than 82% were asymptomatic. (4)Nearly 50% of the children were positive of GAS culture in one year, and the multi-positive was very common in one year. 35% of the children were positive more than two times,26% more than three times,and a few successive in twelve months. (5)During the investigation period,the dominant prevalent strains of GAS were T6,4,1,11,8/25/IMP19 and 5/25/44 in school-age children. There were a significant difference in countryside and in city,and also distribution of T type of the dominant GAS strains had a signi-ficant difference in different years. Conclusions GAS infections are very common among school-age children in Guangzhou. The key to prevent GAS throat infections is to diagnose and treat group A streptococcus pharyngitis promptly,to enhance the healthcare,and to improve the living environments.