A Study of a Recent Outbreak of Acute Hemorrhagic Conjunctivitis at Hyderabad

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Background: Acute hemorrhagic conjunctivitis (AHC) outbreaks were previously associated with adenoviruses; however, Enterovirus 70 (EV70) and Coxsackievirus A24 variant (CV-A24v) are now major causes, belonging to human enteroviruses in the family Picornaviridae. In 2023, an outbreak occurred in Hyderabad, India, with a significantly greater than usual number of AHC cases beginning in August during the rainy season and continuing through September, affecting both sexes and all age groups. Objectives: To identify and characterize viral and bacterial etiological agents associated with the AHC outbreak using culture based and molecular methods. Materials and Methods: A study was conducted at Sarojini Devi Eye Hospital, a tertiary eye care centre in Telangana. Eye swab specimens were collected from 90 patients attending the outpatient department. Samples underwent bacterial culture and sensitivity testing. All samples were screened for COVID-19 using real-time polymerase chain reaction (PCR) at the Viral Research and Diagnostic Laboratory, Osmania Medical College. Pan-enterovirus quantitative PCR (qPCR) was performed to detect enterovirus, followed by genotyping at the National Institute of Virology, Pune. Results: Of the 90 samples tested by pan-enterovirus qPCR, 40 (44.44%) were positive for enterovirus. Genotyping identified all positive samples as Coxsackievirus A24. Bacterial culture detected super-added bacterial infection in 35 (38.89%) patients, with Staphylococcus being predominant. Discussion: Coxsackievirus A24 was the predominant viral agent associated with the outbreak, while super-added bacterial infection was detected in a substantial proportion of patients. Conclusion: Coxsackievirus A24 was the major etiological agent identified during the outbreak. Bacterial culture and molecular testing facilitated comprehensive characterization of the outbreak.