Influenza Outbreak Investigation Report, Thaluang Hospital, Lopburi Province, May 2025
DOI:
https://doi.org/10.59096/wesr.v57i5.7270Keywords:
outbreak, influenza, inpatient Department, hospitalAbstract
Background: On May 21, 2025, the Epidemiology Unit of Thaluang Hospital, Lopburi Province, Thailand was notified of six influenza cases detected by rapid influenza diagnostic test (RIDT). Five cases were inpatients in the male ward, and one case was a patient’s caregiver. The epidemiology team, in collaboration with the hospital infection control unit, conducted an outbreak investigation during May 16–31, 2025, to prevent and control further transmission.
Methods: A descriptive epidemiological study was conducted to describe the outbreak in terms of person, time, and place. In addition, an analytic cross-sectional study was performed to identify risk factors associated with influenza infection. Exposure and outcome variables were collected simultaneously. Associations were analyzed using logistic regression, and odds ratios (ORs) with 95% confidence intervals (95% CI) were reported.
Results: Between May 16 and 31, 2025, a total of eight influenza cases were identified. Laboratory confirmation by RT-PCR detected influenza A virus subtype H1N1 2009 in six cases. Risk factor analysis showed that ‘not wearing a face mask’, ‘close contact with symptomatic individuals’, ‘inconsistent hand hygiene’, and ‘failure to maintain physical distancing’ were significantly associated with influenza infection (p < 0.05).
Conclusions and discussions: This outbreak of influenza in the male ward of Thaluang Hospital was identified as a nosocomial infection caused by influenza A (H1N1 2009). Following the implementation of control and prevention measures, including patient isolation, pre-admission screening, visitor restriction, use of personal protective equipment, and reinforcement of hand hygiene practices, no additional cases were reported after May 31, 2025.
References
Ministry of Public Health (TH), Department of Disease Control. Influenza [Internet]. [cited 2025 Jun 1]. Available from: https://ddc.moph.go.th/disease_detail.php?d=13 (in Thai)
Ministry of Public Health (TH), Department of Disease Control. Influenza situation reports [Internet]. [cited 2025 Jun 1]. Available from: https://dvis3.ddc.moph.go.th/t/DDC_CENTER_DOE/views/DDS2/1_2?%3Aembed=y&%3AisGuestRedirectFromVizportal=y (in Thai)
Department of Control (TH), Division of Epidemiology. Case definition for Communicable Diseases Surveillance, Thailand, 2020. Nonthaburi: Division of Epidemiology, Department of Control (TH); 2020.
World Health Organization. WHO guidelines on hand hygiene in health care. Geneva, Switzerland: World Health Organization; 2009.
Nittayasoot N, Sathawornwiwat A, Voradetwittaya L, Wongwacharapaiboon P, Thammawijaya P. Influenza outbreak in a psychiatric ward of a general hospital, Thailand. Weekly Epidemiological Surveillance Report [Internet]. 2017 [cited 2025 Jun 1];48:11320. Available from: https://he05.tci-thaijo.org/index.php/WESR/article/view/2212/2048 (in Thai)
Jeensavake A, Buachan K. An outbreak investigation of influenza in novices and novice attendants at a summer buddhist novice ordination camp in A temple, Pathum Thani Province, Thailand, from 1 - 30 April 2023. J Raj Pracha Samasai Institute [Internet]. 2025 [cited 2025 Jul 1];9(1):43–54. Available from: https://he04.tci-thaijo.org/index.php/rpsi/article/view/2778 (in Thai)
Bocquet A, Wintenberger C, Lupo J, Morand P, Pavese P, Gallouche M, et al. Description of an influenza outbreak in a French university hospital and risk factors of nosocomial influenza. Eur J Clin Microbiol Infect Dis [Internet]. 2021 [cited 2025 Aug 3];40(1):879–84. Available from: https://link.springer.com/article/10.1007/s10096-020-04070-9
Inthong K, Suphaso W, Kaewkan K. Outbreak investigation of influenza type A in a school, Ban had District, Khonkaen Province, 2-16 November 2022. JODPC8 [internet]. JODPC8 [Internet]. 2023 [cited 2025 Aug 1];2(1):80–95. Available from: https://he03.tci-thaijo.org/index.php/JODPC8/article/view/1265 (in Thai)
Tantirat P, Jamhom S, Kruksomrong J. Investigation of an Influenza A(H3N2) outbreak and assessment of vaccine effectiveness at a non-commissioned officer training center, Saraburi Province, Thailand, 2025. OSIR [Internet] 2025 [cited 2025 Aug 1];18(4):215–23. Available from: https://doi.org/10.59096/osir.v18i4.278748
Yasopa O, Khumphon P, Pacheephet S, Akkapaiboon O, Okada PA, Doungngern P. Epidemiology of influenza from hospital network–based laboratory surveillance, 2017–2021. Weekly Epidemiological Surveillance Report [Internet]. 2023 [cited 2025 Aug 1];54(38):575–86. Available from: https://he05.tci-thaijo.org/index.php/WESR/article/view/673 (in Thai)
Salgado CD, Farr BM, Hall KK, Hayden FG. Influenza in the acute hospital setting. Lancet Infect Dis. 2002 [cited 2025 Aug 1];2(3):145–55. Available from: https://doi.org/10.1016/S1473-3099(02)00221-9 (in Thai)
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