A Community-wide Outbreak of Acute Viral Gastroenteritis in Amphoe Taphan Hin, Changwat Phichit, Thailand, 2006-การสอบสวนการระบาดโรคอุจจาระร่วงเฉียบพลันจากเชื้อไวรัส อำเภอตะพานหิน จังหวัดพิจิตร ประเทศไทย พ.ศ.2549

Abstract

         An epidemiologic investigation on an explosive and widespread outbreak of acute gastroenteritis likely caused by viral infection in Amphoe Taphanhin, Changwat Phichit, Thailand was carried out during 20 February-21 March 2006. Medical records and case investigation reports were reviewed and active case finding was performed. Cases were people who developed a symptom of
watery stool for at least 3 times within 24 hours or had nausea/vomiting. A matched case-control study was conducted with 77 cases and 77 controls; each analytic case definition was the suspected cases who had diarrhea and nausea/vomiting. Controls were randomly selected with age and subdistrict-
matched with cases. Laboratory investigations were performed to identify causative agent. A total of 545 cases were detected (attack rate = 758/100,000). Median age was 12 years (range 1 month-81 years). Incidence rate were highest among those aged 0-1 year (AR = 5,097/100,000),
and 1-4 years (AR = 2,514/100,000), the majority (59%) were female. Hospitalization rate was 15 percent. Symptoms included watery diarrhea (68%), nausea /vomiting (55%), loose stool (54%), and mucous stool (12%). Descriptive data suggested that a municipal market was a common source,
followed by person-to-person transmission within families. The analytic study showed a history of illness in close contact increased risk 4.5 times (95% CI=1.82-11.09) while having any specific food item from the municipal market showed no significant associations. Of the 298 rectal swab culture, 97.7 percent yielded non-enteropathogenic bacteria. Fresh stool specimens examined by polymerase chain reaction was positive for rotavirus in 3 out of 10 (2/4 among age <5 years and 1/6 for age >15 years). Stool specimens negative for bacteria, high percentage of vomiting, short duration of illness, highest incidence in young children, highly contagious nature and positive result for rotavirus combined
to suggest that rotavirus was the cause of this outbreak. After intensive cleaning of the market and household environment at the same time for 2 times and health education target groups, the number of cases decreased to baseline.

Key words: viral gastroenteritis outbreak, market, person-toperson tramission