湖南省O139群霍乱流行因素和快速评估研究

目的了解湖南省O139群霍乱的流行特点,分析流行因素,探索快速有效的监测评估方法和预防控制措施,为制定科学的防控策略提供依据。方法采用回顾性队列研究、生态学研究和现场流行病学调查研究湖南省O139霍乱的流行特点和高发区的流行因素;评估农村集体聚餐卫生指导和管理预防控制措施的效果。分别采用膜免疫层析法和常规细菌分离培养法对腹泻病人及霍乱病人的密切接触者粪便标本进行O139霍乱弧菌检测,以后者为金标准,计算膜免疫层析法的灵敏度和特异度。结果湖南省1997-2009年共发生48起O139霍乱疫情,报告病例103例,带菌者119例,死亡2例,病死率为1.94%。在局部地区有集中发生趋势。2002-2009年常规监测腹泻病人阳性率为2.47/万,水产品样阳性率为0.57%,疫点监测检测人群阳性率为1.18%,外环境阳性率为3.44%;非疫点地区水体环境中未检测到霍乱弧菌。48起疫情中暴发16起,散发32起,28起疫情与农村集体聚餐有关。2003年9起暴发疫情中参与聚餐人员的O139霍乱弧菌感染率为5.46%,食用聚餐剩菜人员的感染率为9.23%,未食用聚餐食物人员的感染率为0,病人和带菌者分离到的O139霍乱弧菌和甲鱼中菌株的PFGE图谱相同。高发区农村聚餐中使用甲鱼和食品制作生熟不分的比率、人均甲鱼消耗量、甲鱼中O139霍乱弧菌检出率均高于低发区。高发区采取农村集体聚餐卫生指导和管理措施后,农村厨师和就餐人群的卫生习惯改善,未再发现疫情。膜免疫层析法检测病例粪便标本中灵敏度为100%,特异度为95.20%,45份实验室霍乱弧菌培养阳性的甲鱼和外环境标本经二次增菌培养,试纸条检测结果为阴性。结论湖南省1997-2009年的O139霍乱疫情呈低流行水平;O139霍乱疫情的发生主要跟食用被霍乱弧菌污染的水产品特别是甲鱼有关,以农村集体聚餐卫生指导和管理为主的综合性预防控制措施是预防O139霍乱疫情发生的有效措施;膜免疫层析法可适用于各医疗机构的腹泻病门诊患者的快速筛查和评估。

Epidemic Factors and Rapid Assessment of Vibrio cholerae O139 in Hunan Province

Objective To understand the epidemic characteristics of Vibrio cholerae O139 in Hunan Province,to analyze the epidemic factors,to explore rapid effective monitoring evaluation methods and preventive control measures,and to provide a scientific basis for making the prevention and control strategy.Methods Retrospective cohort study,ecology methods and field epidemiology methods had been used for the investigation of cholera O139 epidemic features and epidemic factors in high incidence areas in Hunan Province,and the assessment of prevention and control measures such as guidance and management to the health of rural group dinner.Membrane immunochromatography assay and conventional bacterial isolation and culture methods were used for testing cholera O139 in stool specimens from patients with diarrhea and individuals with history of close contact with cholera patients.The latter methods were taken as the gold standard to calculate the sensitivity and specificity of membrane immunochromatography assay.Results There were 48 cholera O139 outbreaks in Hunan Province from 1997 to 2009,involving 103 cases,119 carriers,and 2 deaths,with the mortality rate of 1.94%.Cases trended to cluster in some areas.From 2002 to 2009,in routine monitoring,cholera O139 cases in patients with diarrhea was 2.47/10,000 population,the positive rate of cholera O139 strains in aquatic products was 0.57%,the positive rate of population in places with cholera outbreak was 1.18%,and the positive rate of outer environment was 3.44%.Vibrio cholerae had not been detected in the water and environment in non-epidemic areas.16 of 48 outbreaks were cluster-associated,32 outbreaks were sporadic,and 28 outbreaks were related to rural group dinner.In 2003,the infection rate of persons participated in dinner gathering was 5.46% in 9 cluster-associated outbreaks.The infection rate of persons with consumption of dinner leftovers was 9.23%.The infection rate of persons that did not eat dinner was 0.00%.Cholera O139 strains that isolated from patients,carriers and soft-shelled turtles had the same PFGE pattern.The ratio of consumption of soft-shelled turtles and regardless of raw and cooked food in food production,the per capita consumption of soft-shelled turtles and the detection rate of cholera O139 in soft-shelled turtles in the high incidence areas were higher than those in the low incidence areas.Since the application of rural group dinner health guidance and management measures,the hygiene practices of rural cook and eaters had been improved,and the disease had not been detected in high incidence areas.The sensitivity of membrane immunochromatography assay for stool specimens was 100%,and the specificity was 95.20%.45 specimens that were culture positive for cholera from soft-shelled turtles and the outer environment tested negative by test strips after the second bacteria-proliferating.Conclusions Cholera O139 was at a low endemic level in Hunan Province from 1997 to 2009.Cholera O139 epidemic occurred mainly with the consumption of cholera contaminated seafood,especially soft-shelled turtles.Integrated prevention and control measures mainly as guidance and management to the health of rural group dinner were the effective measures to prevent outbreak of cholera O139.Membrane immunochromatography assay was applicable to all medical institutions for rapid screening and evaluating outpatients with diarrhea.