District Nodal officer Ardram mission, Pathanamthitta, Health services, Kerala, India.
Consultant, ICMR-National Institute of Epidemiology, Chennai, Tamil Nadu, India.
J Infect Public Health. 2024 Dec;17(12):102568. doi: 10.1016/j.jiph.2024.102568. Epub 2024 Oct 18.
In July 2021, the Alappuzha district in Kerala, India, reported an unexpected number of acute gastroenteritis (772) cases (Outbreak A). On October 10, 2021, a university in Wayanad, Kerala, reported 25 acute gastroenteritis cases (Outbreak B). We described both the outbreaks and determined the agent, source and risk factors.
We defined a suspected case as the occurrence of vomiting or at least three episodes of loose stools within 24 h and a confirmed case as those with stool samples/rectal swabs positive for norovirus. We did a matched case-control study in Outbreak A and a retrospective cohort study in Outbreak B. We calculated the adjusted odds ratio (aOR) in outbreak A, relative risk (aRR) in outbreak B and population attributable fraction (PAF). We tested stool and water samples for bacteria and viruses.
We identified Group II norovirus in stool samples in both outbreaks and 4/5 water samples in Outbreak A. Suspected norovirus infection was associated with drinking inadequately boiled water from the municipal water supply in outbreak A [aOR: 4.5; 95 % C.I: 1.2-15.8; PAF: 0.23] and well water in hostels in outbreak B [aRR: 2.2; 95 % C.I: 1.2-3.9; PAF: 0.15]. In Outbreak A, groundwater from tube wells was mixed in the municipal water supply overhead tanks without chlorination.
The gastroenteritis outbreaks were caused by Group II norovirus due to the consumption of inadequately boiled contaminated groundwater (outbreak A) and well water (outbreak B). We recommended superchlorination of overhead tanks and wells and boiled water for drinking.
2021 年 7 月，印度喀拉拉邦阿拉普扎地区报告了一起急性肠胃炎（772 例）的意外病例（暴发 A）。2021 年 10 月 10 日，喀拉拉邦瓦亚纳德的一所大学报告了 25 例急性肠胃炎病例（暴发 B）。我们描述了这两起暴发疫情，并确定了病原体、来源和危险因素。
我们将疑似病例定义为在 24 小时内发生呕吐或至少 3 次腹泻，并将确诊病例定义为粪便样本/直肠拭子诺如病毒检测阳性的病例。我们在暴发 A 中进行了病例对照研究，在暴发 B 中进行了回顾性队列研究。我们计算了暴发 A 中的调整比值比（aOR）、暴发 B 中的相对风险（aRR）和人群归因分数（PAF）。我们对粪便和水样进行了细菌和病毒检测。
我们在两起暴发疫情的粪便样本中均检测到了 II 组诺如病毒，在暴发 A 的 5 份水样中有 4 份检出。在暴发 A 中，疑似诺如病毒感染与饮用未充分煮沸的市政供水[比值比（aOR）：4.5；95%置信区间（C.I.）：1.2-15.8；人群归因分数（PAF）：0.23]和宿舍井水有关，在暴发 B 中与饮用井水有关[相对风险（aRR）：2.2；95%置信区间（C.I.）：1.2-3.9；人群归因分数（PAF）：0.15]。在暴发 A 中，地下水从管井中混入了市政供水的高架水箱中，未进行氯化处理。
这两起肠胃炎暴发疫情是由 II 组诺如病毒引起的，原因是饮用了未充分煮沸的受污染地下水（暴发 A）和井水（暴发 B）。我们建议对高架水箱和水井进行超氯化处理，并饮用煮沸的水。
