Norovirus Cluster in an Elementary School in Changhua, 2012

Shih-Tse Huang1, Chen-Pei Lin2, Yi-Chun Lo1, Dah-Shyong Jiang1

2012 Vol.28 NO.7

Correspondence Author: Shih-Tse Huang

  • 1. Field epidemiologist Training Program, Centers for Disease Control, Taiwan
  • 2. Third branch, Centers for Disease Control, Taiwan


Since afternoon of February 22, 2012, an elementary school informed authorities of possible food-poisoning cluster in Changhua. Many people presented vomiting, diarrhea and abdominal pain. To estimate the scope, identify the etiological pathogen, determine the responsible food item and provide recommendation, the public health authorities conducted an epidemiologic investigation. The investigation method including: (1)interview with teachers; (2)questionnaire for teachers and 3 to 6 grades students; (3)anal swab and stool from cases; and (4)suspected residual foods and water sampling. Laboratory examination included Bacillis cereus, Staphylococcus aureus, pathogenic Escherichia coli, Vibrio parahaemolyticus, Salmonella, and Norovius. The definition of investigated case was having one of the gastroenteritis symptoms (diarrhea, vomiting and abdominal pain) after lunch on February 21, 2012. However, case accompanied with rhinorrhea was excluded. Among eighty investigated cases, 56.2% presented diarrhea, 66.3% presented vomiting and 8.8% presented fever. The median incubation time was 34 hours. Questionnaire analysis did not find out responsible food. Stool sample from one cook and two students revealed norovirus. According to the symptoms, incubation time and stool analysis, we concluded the cluster was related to norovirus gastroenteritis. The school lunch contaminated directly or indirectly by norovirus-infecting cook was the source. We recommend the school to enforce preventing manners as following: (1)Clean hands with soap and dry hands after toilet and before cooking. (2)Teachers and students should clean hands with soap and dry hands before meal and after toilet. (3)If cook has gastroenteritis symptoms, stop food management. He could start to work 48 hours after symptoms resolving.