Gertler Maximilian, Dürr Matthias, Renner Peter, Poppert Sven, Askar Mona, Breidenbach Janina, Frank Christina, Preußel Karina, Schielke Anika, Werber Dirk, Chalmers Rachel, Robinson Guy, Feuerpfeil Irmgard, Tannich Egbert, Gröger Christine, Stark Klaus, Wilking Hendrik
Department for Infectious Disease Epidemiology, Robert Koch Institute (RKI), Seestraße 10, 13353, Berlin, Germany.
Postgraduate Training for Applied Epidemiology, affiliated to the European Programme for Intervention Epidemiology Training, European Centres of Disease Controle (ECDC), Sweden, Europe.
BMC Infect Dis. 2015 Feb 22;15:88. doi: 10.1186/s12879-015-0807-1.
During weeks 32-33, 2013, 24 cases of cryptosporidiosis were notified in the city of Halle (annual mean 2008-2012: 9 cases). We investigated the outbreak to identify the source and recommend control measures, considering that between weeks 23-25 the river Saale which flows through the city centre overflowed the floodplain, parts of the city centre and damaged sewage systems.
We defined a case as a resident of Halle with gastroenteritis, Cryptosporidium-positive stool and disease onset weeks 27 through 47. In a case-control study among kindergarten children, we compared cases and controls regarding environmental exposure, use of swimming pools, zoo visits and tap water consumption 14 days pre-onset or a corresponding 14-days-period (controls) and adjusted for residence. Stool specimens were tested by microscopy and PCR, and Cryptosporidium DNA was sequenced. Samples from public water system, swimming pools and river Saale were examined for Cryptosporidium oocysts (microscopy and PCR).
Overall, 167 cases were detected, 40/167 (24%) were classified as secondary cases. First disease onsets occurred during week 29, numbers peaked in week 34 and started to decrease in week 36. Median age was 8 years (range: 0-77). Compared to controls (n = 61), cases (n = 20) were more likely to report visits to previously flooded areas (OR: 4.9; 95%-CI: 1.4-18) and the zoo (OR: 2.6; 95%-CI: 0.9-7.6). In multivariable analysis visits to the floodplain remained the sole risk factor (OR: 5.5; 95%-CI: 1.4-22). Only C.hominis of a single genotype (IbA9G2) was detected in stools. Oocysts were detected in samples from the river, two local lakes and three public swimming pools by microscopy, but not in the public water supply.
Evidence suggests that activities in the dried out floodplain led to infection among children. Secondary transmissions may be involved. Consequently, authorities recommended to avoid playing, swimming and having picnics in the flood-affected area. Health authorities should consider the potential health risks of long-term surviving parasites persisting on flooded grounds and in open waters even several weeks after the flooding and of bathing places close to sewage spill-overs. Preventive measures comprise water sampling (involving parasites), information of the public and prolonged closures of potentially contaminated sites.
2013年第32 - 33周期间，哈雷市通报了24例隐孢子虫病病例（2008 - 2012年年均病例数为9例）。鉴于在第23 - 25周期间，流经市中心的萨勒河淹没了洪泛区、市中心部分区域并损坏了污水系统，我们对此次疫情进行了调查，以确定传染源并推荐防控措施。
我们将病例定义为哈雷市居民，患有肠胃炎、粪便隐孢子虫检测呈阳性且发病时间在第27至47周。在一项针对幼儿园儿童的病例对照研究中，我们比较了病例组和对照组在发病前14天或相应的14天时间段（对照组）内的环境暴露情况、游泳池使用情况、动物园参观情况和自来水饮用情况，并根据居住地进行了调整。粪便样本通过显微镜检查和聚合酶链反应（PCR）进行检测，隐孢子虫DNA进行了测序。对公共供水系统、游泳池和萨勒河的样本进行了隐孢子虫卵囊检测（显微镜检查和PCR）。
总体共检测到167例病例，其中40/167（24%）被归类为二代病例。首例发病发生在第29周，病例数在第34周达到峰值，并在第36周开始下降。中位年龄为8岁（范围：0 - 77岁）。与对照组（n = 61）相比，病例组（n = 20）更有可能报告去过先前被洪水淹没的地区（比值比：4.9；95%置信区间：1.4 - 18）和动物园（比值比：2.6；95%置信区间：0.9 - 7.6）。在多变量分析中，前往洪泛区仍然是唯一的危险因素（比值比：5.5；95%置信区间：1.4 - 22）。粪便中仅检测到单一基因型（IbA9G2）的人隐孢子虫。通过显微镜检查在河流、两个当地湖泊和三个公共游泳池的样本中检测到了卵囊，但在公共供水系统中未检测到。
有证据表明，在干涸的洪泛区开展的活动导致儿童感染。可能涉及二代传播。因此，当局建议避免在受洪水影响的地区玩耍、游泳和野餐。卫生当局应考虑到即使在洪水过后数周，长期存活于被洪水淹没的地面和开放水域以及靠近污水溢流处的浴场中的寄生虫对健康的潜在风险。预防措施包括水样采集（检测寄生虫）、向公众提供信息以及延长对潜在污染场所的封闭时间。
