An Outbreak of Hepatitis A due to consumption of wedding party food prepared from an unchlorinated well-water, Naripetta, Kozhikode district, Kerala, India, November 2019–January 2020

  • Water or foodborne
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Background:
Hepatitis A (HAV) causes 5-15% of acute liver failure cases in India. On December 4, 2019, the District Surveillance unit notified a cluster of HAV cases in Naripetta, Kozhikode, Kerala. We investigated to identify potential exposures and propose recommendations.

Methods:
We defined a case as fever/jaundice/dark urine in any resident of Naripetta, November 2019-January 2020. We conducted an active case search. We described the cases by date of symptoms onset and plotted by their residence. We calculated the attack rate by age and gender. We conducted a case-control study to test the generated hypothesis. We defined 'case' as HAV case; and 'control' as an individual without HAV in a resident of Naripetta, November 2019-January 2020. We calculated the odds ratio (OR), adjusted OR (aOR), and 95% confidence interval (95%CI). We examined dose-response and performed chi-square test for trend.

Results:
The attack rate of HAV was 2 per 1000 (60/24,833). The attack rate was higher among aged 15-29 years (5 per 1000) and males (3 per 1000). Among the 60 cases, 52 (87%) had jaundice, and 33 (55%) hospitalized. All 60 cases attended a wedding party in November 2019. Epicurve suggested a point-source outbreak, and cases reported following the wedding party. We generated a hypothesis as water/food served during a wedding party could be potential exposure. We recruited 60 cases and 171 controls. Salad [aOR= 3.0, 95%CI= 1.02-8.8] and alcohol with water [aOR= 2.4, 95%CI= 1.1-5.5] were significantly associated with HAV. Odds of HAV increased with an increase in exposures [salad nor alcohol (OR=1 (Ref.), alcohol (OR=2.8), salad (OR=4.9), salad and alcohol (OR=11.4), Chi-square=15.8, p<0.001]. We found that unchlorinated well water was used to prepare salad and alcoholic drinks.

Conclusions:
Consumption of salad and alcoholic drinks prepared from the unchlorinated well water caused HAV outbreak in Naripetta. We recommended using chlorinated well water.

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