Outbreak investigation of Influenza A H1N1 in primary school A, Samrong Subdistrict, Non Thai District, Nakhonratchasima Province, Thailand, 1–25 February 2025
DOI:
https://doi.org/10.59096/wesr.v56i9.5437Abstract
Background: On February 17, 2025, the Situational Awareness Team of Non Thai District received reports of multiple cases of influenza among students at a primary school in Samrong Subdistrict, Non Thai District, Nakhon Ratchasima Province. A disease investigation team conducted fieldwork to confirm the outbreak and diagnosis, describe the outbreak characteristics, identify risk factors, and propose prevention and control measures.
Methods: The study involved a review of medical records, case finding, descriptive epidemiology, and analytical epidemiology using a case–control study design (1 : 2). The case group included suspected, probable, and confirmed cases among students, teachers, and school staff, based on descriptive epidemiological findings. The control group included students, teachers, and staff without symptoms based on patient definitions. Data analysis utilized multiple logistic regression. Additionally, environmental surveys of the school and personal hygiene assessments were conducted.
Results: A total of 61 individuals met the case definition, including 13.11% confirmed cases, 31.15% probable cases, and 55.74% suspected cases, with the majority being Grade 1 students. The specific attack rate was 86.95%. No severe cases or fatalities were reported. Laboratory testing of 8 samples confirmed influenza A (H1N1) virus in all samples. Analytical epidemiology revealed statistically significant associations with shared transportation with infected individuals (Adjusted odds ratio = 1.90, 95% CI = 1.10–3.20) and having infected family members (Adjusted odds ratio = 1.75, 95% CI = 1.02–3.00).
Conclusion and Recommendations: An outbreak of Influenza A (H1N1) has been detected at a primary school in Samrong Subdistrict, Non Thai District, Nakhon Ratchasima Province. Close contact with influenza patients is a statistically significant risk factor for transmission. The measures that were implemented were able to stop the outbreak cycle in the school. It is recommended that a disease surveillance system be established within the school, alongside providing health education and promoting personal hygiene among students, in order to encourage positive health behavior changes.
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