Outbreak Investigation of Acute Hemorrhagic Conjunctivitis Caused by Coxsackievirus A24 Among Wrestling Event Participants in Mueang District, Phetchabun Province, Thailand, June 2023

Abstract

On June 25, 2023, the Epidemiology Unit of Phetchabun Hospital was notified of an outbreak of conjunctivitis among participants in a wrestling competition in Mueang District, Phetchabun Province. A surveillance and rapid response team, in collaboration with relevant authorities, conducted an investigation from June 25 to June 30, 2023, to confirm the diagnosis and outbreak, describe the epidemiological characteristics, identify associated factors, and provide recommendations for controlling and preventing further spread. A descriptive epidemiological study defined suspected cases as individuals who participated in the wrestling competition and exhibited conjunctival inflammation between June 17 and June 30, 2023. Conjunctival swabs and water samples were collected to identify pathogens and assess chlorine residues. An unmatched case-control study was conducted, with logistic regression used to analyze the associated factors. The investigation identified 50 patients, with a male-to-female ratio of 2.8:1 and a mean age of 15 years (SD = 4.5). The predominant symptom was conjunctival redness (100%), followed by discharge (68%) and eye irritation (44%). The first cases were reported on June 21, with the peak occurring on June 25. Conjunctival swab tests confirmed Coxsackievirus A24 as the causative agent, and the water chlorine concentration was found to be 0.2 mg/L. Multivariate analysis revealed significant associated factors for the outbreak, including training in the same group (Adjusted OR = 8.26, 95% CI: 2.36–29.98, P-value < 0.001) and sharing meals (Adjusted OR = 17.14, 95% CI: 2.16–136.05, P-value = 0.01). The outbreak was attributed to Coxsackievirus A24, likely introduced from outside the area, with close contact, such as training together and sharing meals, as major contributing factors. Screening symptomatic individuals and isolating patients from the general population are essential measures to prevent future outbreaks.