Outbreak investigation of influenza type A in a school, Ban had district, Khonkaen province, 2-16 November 2022

Abstract

Investigation Report on Influenza Outbreak in a School in Ban Had District, Khon Kaen Province   Introduction: Between 2-16 November 2022, an influenza outbreak occurred in a school located in Ban Had District, Khon Kaen Province. The primary objectives of this investigation were to confirm the diagnosis of influenza, ascertain the outbreak's presence, study the nature and cause of the outbreak, and formulate guidelines for disease control and prevention. Methods:Several methods were employed in this investigation: Descriptive Epidemiology: Patient medical histories were collected by interviewing both students and staff. Data from patients were compared to the median values of the past 5 years to identify any significant deviations. Analytical Epidemiology: A retrospective study with a control group was conducted to delve deeper into the outbreak's risk factors. This allowed for a more in-depth analysis of the causes and contributing elements. Laboratory Study: Samples were collected to detect the genetic material of the influenza virus using the RT-PCR method, providing essential information about the virus strain responsible for the outbreak. Findings:From the investigation, it was discovered that 153 individuals exhibited influenza symptoms out of a total population of 784 people, resulting in a morbidity rate of 19.52%. The gender ratio was approximately 1:1.19 (male to female). Common symptoms included fever, cough, and nasal discharge, with the latter present in 90.2% of cases. Primary 4 and 6/1 students were the most affected groups, accounting for 9.80% of cases. The highest prevalence was found among Parichart students, with 16.34% affected. Laboratory tests identified the genetic material of the seasonal influenza virus type A, specifically strain H3. Risk Factors and Protective Measures: Risk factors contributing to the outbreak included close contact with symptomatic individuals (OR=4.96, 95%CI=3.21-7.65), sharing eating utensils (OR=6.19, 95%CI=3.27-11.7), and using clothing together (OR=4.21, 95%CI=1.41-12.54). Protective factors observed included wearing a mask (OR=0.47, 95%CI=0.30-0.74), frequent hand washing (OR=0.37, 95%CI=0.25-0.52), and social distancing (OR=0.14, 95%CI=0.09-0.21). Disease Control and Prevention:  After the implementation of disease prevention and control measures, the outbreak began to subside, with the last patient identified on November 16, 2022. Subsequent surveillance over the next 14 days revealed no new cases, indicating the effectiveness of the measures taken. Recommendations: Based on the findings, it is recommended that the National Tobacco Products Control Board, in collaboration with local authorities, continue to enforce and promote preventive measures, such as wearing masks, regular hand washing, and maintaining social distancing. Additionally, educating the community about influenza prevention strategies and raising awareness about the importance of hygiene can further reduce the risk of future outbreaks.