Public Health Agency of Sweden, Solna, Sweden.
European Programme for Intervention Epidemiology Training (EPIET), European Centre for Disease Prevention and Control (ECDC), Solna, Sweden.
Euro Surveill. 2022 Jun;27(22). doi: 10.2807/1560-7917.ES.2022.27.22.2100918.
In autumn 2019, the Public Health Agency of Sweden identified a cluster of Newport cases by whole genome sequencing (WGS). Cases' distribution in place and time indicated a nation-wide ongoing outbreak. An investigation was initiated to identify the source and prevent further cases. We conducted a case-case study based on notified salmonellosis cases and a trawling questionnaire, comparing 20 outbreak cases and 139 control cases. Food exposures were compared by adjusted odds ratios (aOR) with 95% confidence interval (CI) using logistic regression. Implicated foods were sampled. Outbreak cases were more likely to have consumed crayfish (aOR = 26; 95% CI: 6.3-105). One specific brand of imported frozen, pre-cooked whole crayfish in dill brine was identified as the source. Newport was later detected in different batches from retail and in one sample from border control. Isolates from food samples clustered with the human outbreak strain by WGS. Although the retailer made a complete recall, two more cases were identified long afterwards. This investigation demonstrated the successful use of a case-case study and targeted microbiological testing to identify the source. The immediate action taken by the retailer was important to confirm the source and stop the outbreak.
2019 年秋季，瑞典公共卫生局通过全基因组测序（WGS）发现了一批纽波特沙门氏菌病例。病例的时空分布表明全国范围内正在发生暴发。因此开展了一项调查，以确定源头并防止进一步发生病例。我们基于通报的沙门氏菌病例和拖网调查问卷进行了病例对照研究，比较了 20 例暴发病例和 139 例对照病例。采用逻辑回归法，通过调整比值比（aOR）和 95%置信区间（CI）比较了食物暴露情况。对可疑食物进行了采样。暴发病例更有可能食用了小龙虾（aOR=26；95%CI：6.3-105）。一种特定品牌的进口冷冻、预煮、整只小龙虾，用莳萝盐水腌制，被确定为来源。纽波特沙门氏菌后来在不同批次的零售产品和一次边境控制样本中被检测到。食品样本中的分离株通过 WGS 与人类暴发菌株聚类。尽管零售商进行了全面召回，但在那之后又发现了两例病例。该调查证明了病例对照研究和目标微生物学测试可成功用于确定源头。零售商立即采取行动对于确认源头和阻止疫情爆发非常重要。
