An outbreak investigation of influenza B in a government primary school, Muang District, Pattani Province, Thailand, 25th January–4th February 2019

Abstract

Background: On 25th January 2019, the Surveillance Rapid Respond Team (SRRT) ofthe Muang Pattani District Public Health Office was notified that the cluster of influenza-like illness (ILI) cases were found in a school (kindergarten 1-3 and prathom 1-6 program). The objectives were to confirm the outbreak, describe epidemiologic characteristics, determine source cases and risk factors, and implement outbreak control as well as prevention measure.
Methods: A descriptive epidemiologic study was carried out. ‘Suspected case’ was defined as student, teacher or school personnel who had fever with at least one symptom of the followings; cough, sore throat, runny nose, sputum, myalgia or headache during 9 January to 4 February, 2019. ‘Confirmed case’ was suspected case who had laboratory showed influenza virus infection. The procedures were including medical record review, interviews with patients, active case finding program, laboratory examination, and environmental survey.
Results: A total of 112 suspected influenza cases were identified, three confirmed cases who had positive laboratory confirmation. The attack rate was 5.52% (112/2,028) with no dead case reported. All of those cases (100%) have the history of fever. In addition, the majority of those also had the symptoms of runny nose and cough (83.92% and 83.03% respectively). The high attack rate was observed among the kindergarten students year 1 to 3 compared with students prathom 1 to 6, which was found in kindergarten students year 3 (17.01%), followed by those of year 1 and 2 (13.48% and 12.69% respectively). Crucial factors influenced this outbreak were including 1) The first case (a kindergarten teacher) worked normally and had contact with several people at the school while she was sick 2) The kindergarten students performed daily activities together and they used the same toys, learning stuff, and the playground without adequate cleaning. One week school closure was implemented to control the outbreak.
Conclusions & Discussions: This outbreak was caused by Influenza B. In the future, one–week school break is supposed to be one of the key disease control interventions in a school setting that should be highlighted and executed as soon as the influenza outbreak affirmed.