An outbreak investigation of hepatitis A in personnel of one company, Samut Prakan Province, Thailand, October 2018

Abstract

Background: On 4 October 2018, the Bureau of Epidemiology (BoE) was notified of hepatitis A outbreak involving 28 personnel of one company in Samut Prakan Province. All cases occurred only in one department of the company, who attended the meeting in Nakhon Nayok Province during 25-26 August 2018. During the meeting, they had history of food consumption at resort B, restaurants C and D. The Joint Investigation Team investigated to verify diagnosis and outbreak, determine epidemiological characteristics of the outbreak, find the source and transmission, and recommend control measures.
Methods: The investigation included medical record review of the sick personnel in the affected company, active case finding in the company, resort B, restaurants C and D, and sample collection from the suspected cases, drinking and nondrinking water, water source, ice, and some raw food. Environmental investigation was also conducted in the company in Samut Prakan Province, resort B and restaurants C, D in Nakhon Nayok Province.
Results: Of 292 personnel who attended the meeting in Nakhon Nayok Province, 55 (18.8%) were identified. Of them were 48 suspected cases and 7 confirmed cases. Male to female ratio was 1 : 1.9. The age ranged between 23-53 years old with a median of 36 years. Clinical manifestations were fever (96.3%), fatigue (94.3%), anorexia (77.4%), dark urine (73.9%), nausea (69.8%), and jaundice (58.5%). The first case had onset on 10 September 2018, about 15 days after the meeting, and the last case developed symptoms on 12 October 2018. An investigation identified 1 food handler with asymptomatic hepatitis A in restaurant C and also 2 water samples for use in this restaurant. The water source was from the shallow well 10-15 meters away from the toilets and with no chlorination.
Conclusions: This confirmed hepatitis A outbreak among the personnel of the company might be due to exposure to contaminated food in restaurant C. Contaminated water for food preparation might be the source of infection. Food and environmental sanitation, personnel hygiene, and standards of clean food good taste in the restaurants and food shops are helpful for disease prevention.