Outbreak Investigation of Influenza and Pneumonia in a Prison in Mueang Udon Thani district, Udon Thani Province

Abstract

A disease investigation of influenza and pneumonia was conducted at a prison in Udon Thani province during March 12–21, 2024. The objectives were to confirm the diagnosis and outbreak, describe the distribution of the disease by person, place, and time, identify potential risk factors, and propose appropriate control measures. A descriptive epidemiological approach was applied using descriptive statistics, including number, attack rates, and dormitory density. An analytical epidemiological study using a case-control design was conducted to identify risk factors associated with the occurrence of influenza in a prison setting. Inferential statistics were applied, and the results were presented using odds ratios (OR), 95% confidence intervals (CI), and P-value. As a result of the investigation identified a total of 106 cases from February 25 to March 21, 2024. Average age = 33.8 years (SD = 9.83) and median age = 31 years (min 18 years, max 56 years). The data from 84 patients show that most patients have symptoms of cough (89.29%), sore throat (76.19%), headache (64.29%), and high fever (60.71%). The survey of personal hygiene factors among prisoners in the patient group and the non-ill inmate group, with 84 individuals in each group. The most risk factor among the patient group was sleep within 1 meter of symptomatic individuals (46.43%). The most factor for non-ill inmate group was sleep more than 1 meter from symptomatic individuals (34.53%). Multivariable analysis using conditional multiple logistic regression identified several factors significantly associated with influenza and pneumonia at the 0.05 level. These included: sleep within 1 meter of symptomatic individuals (Adj OR = 2.23, 95%CI = 1.27-4.71), engaging in activities with the patient (Adj OR = 4.59, 95%CI = 2.05-10.97), and sharing spoons (Adj OR = 3.52, 95%CI = 1.35-10.19). The results of the density of prisoners per dormitory area and air-circulation rate did not meet the standard values. This likely contributed to the airborne transmission of the virus and exposure to droplets from the patients through shared activities and objects. Following the joint disease control measures implemented by the prison, the field investigation team from the Office of Disease Prevention and Control 8, Udon Thani, and relevant agencies, the outbreak was brought under control. Appropriate surveillance, prevention, and control measures for respiratory infectious diseases in the prison were established, including designating isolation areas for symptomatic individuals and monitoring high-risk groups, improving ventilation in dormitories, enhancing preventive measures by mandating that all inmates wear face masks at all times and refrain from sharing personal items, particularly eating utensils.