Objective A hepatitis A outbreak in a primary school was reported by Gan County Center for Disease Control and Province (CDC) and an investigation was conducted to identify the possible source of infection and risk factors for transmission.Methods A probable case was defined as having onset of jaundice (yellow urine,sclera or skin) or a 2-fold increase in Alanine aminotransferase with 2 or more,of the followings symptoms:anorexia,disgust of oil,abdominal pain,nausea,fatigue,vomiting,in students and staff of the primary school between 1 November 2008 and 14 February 2009.A confirmed case was IgM positive for hepatitis A,added on a probable case.We searched for cases through reviewing medical records in the township hospital and village clinics and conducting symptom screening among students or teachers.We also conducted a case-control study to compare the exposure histories of 19 cases and 53 anti-HAV-IgM negative controls randomly selected from those asymptomatic students in the same grade.Results 21 cases from all the students was identified,with the attack rate as 3.5％.The epidemic curve showed the two peaks of the outbreak were 28 days apart,both indicating that they were related to the exposure of the source of origin.74％of the case-students drank the unboiled Well B water,compared to 42％ of control-students (OR=4.0,95％CI:1.1-15).The total bacterial count was 600 cfu/ml and the total coliform was 23 MPN/100 ml in one sample collected from the well water.Conclusion This hepatitis A outbreak was caused by drinking contaminated water in Well B.We recommended that all the schools should use chlorinated municipal pipe water.Public health authorities should strengthen the supervision of quality of water in schools.%目的 对江西省赣县某农村小学甲肝暴发进行调查,查找危险因素和传播途径,并提出针对性预防控制措施.方法 调查疑似病例为2008年11月1日至2009年2月14日期间,该校师生中符合下列任何之一者:(1)出现黄疸(尿、巩膜或皮肤黄染)者.(2)丙氨酸氨基转移酶(ALT)出现2倍及以上升高并具有≥2项下列症状者:纳差、厌油、腹痛、恶心、乏力、呕吐.确诊病例为疑似病例并甲肝病毒IgM抗体阳性者.通过查阅乡镇卫生院和村诊所门诊记录、对学校师生开展症状筛查,进行病例搜索.开展病例对照研究,比较病例组和对照组(从同年级无症状、IgM阴性的学生中随机选取)的危险因素暴露情况.结果 共搜索到21例甲肝病例,均为小学生,罹患率为3.5％.流行曲线呈现两个高峰,间隔28 d,均为点源暴露模式.病例对照研究显示,饮用B井生水是发病危险因素(0R=4.0,95％CI:1.1～ 15).B井水检测细菌总数600 cfu/ml,大肠菌群23 MPN/100 ml.结论 本次甲肝暴发系因饮用被污染的B井生水所导致.建议学校改用经过统一消毒的管网自来水,公共卫生部门应加强学校饮水的卫生监督.
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