# Acute haemorrhagic conjunctivitis outbreak attributed to coxsackievirus A24 in Ratanakiri, Cambodia, 2023

## TL;DR

A 2023 outbreak of acute haemorrhagic conjunctivitis in Cambodia was caused by coxsackievirus A24, with risk factors including poor hygiene and contact with infected people.

## Contribution

Identified coxsackievirus A24 as the causative agent and quantified key risk factors for AHC transmission in a rural Cambodian setting.

## Key findings

- Coxsackievirus A24 was confirmed as the primary cause of the AHC outbreak using RT–PCR and RNA sequencing.
- Physical contact with infected individuals and poor hand hygiene were significant risk factors for AHC.
- The overall attack rate in the village was 12.3% during the outbreak.

## Abstract

To determine the causative agent, clinical manifestations and risk factors for infection during a September 2023 outbreak of acute haemorrhagic conjunctivitis (AHC) in Pak Touch village, Ratanakiri province, Cambodia.

A retrospective case-control study was conducted. Cases were age-matched to controls (1:1), who were randomly selected from the village population. Twenty-one conjunctival samples were analysed using real-time reverse transcription–polymerase chain reaction (RT–PCR). RNA sequencing was additionally performed to identify the causative agent of the outbreak. Logistic regression models were used to identify significant risk factors.

A total of 73 cases and 73 controls were included in the analysis. Cases had a median age of 20 years (range: 1–70, mean and standard deviation: 27.7 ± 20.0), and 46.6% (34/73) were male. The overall attack rate was 12.3% (73 cases/594 residents). Clinical presentations included conjunctival hyperaemia (100%), subconjunctival haemorrhage (82.2%, 60), pain and discharge (64.4%, 47 each), eyelid swelling (57.5%, 42) and tearing (54.8%, 40). RT–PCR identified enterovirus in 52.4% (11/21) of conjunctival swabs, with RNA sequencing confirming the coxsackievirus A24 variant as the causative agent in five swabs. Statistical analysis identified significant risk factors, including physical contact with patients with acute haemorrhagic conjunctivitis (adjusted odds ratio [aOR]: 4.42, 95% confidence interval [CI]: 1.90–10.10), frequent eye rubbing (aOR: 4.56, 95% CI: 2.00–10.37) and poor hand hygiene (aOR: 3.70, 95% CI: 1.64–8.43).

The outbreak of acute haemorrhagic conjunctivitis in Pak Touch village was primarily caused by coxsackievirus A24. Significant risk factors included physical contact with infected individuals, frequent eye rubbing and poor hand hygiene. Effective hygiene measures are crucial to prevent the spread of AHC.