Molecular analysis of acute hemorrhagic conjunctivitis in a tertiary care hospital, Kalburgi district, Karnataka 2023.

Introduction: Viral infections are the predominant cause of acute hemorrhagic conjunctivitis (AHC) across the globe. From July to August of 2023, a large-scale conjunctivitis outbreak was witnessed in India, affecting a large number of individuals. The present study was initiated to identify the causative agent responsible for the AHC outbreak in Kalburgi district of Karnataka state.

Methodology: Conjunctival and throat swabs were collected from AHC patients from a tertiary care hospital in Kalburgi from August to September 2023. After total viral RNA extraction from all the samples, reverse transcriptase PCR was performed using 5' non-coding regions of the enterovirus (EV) genome. The positive samples were further subjected to PCR using EV type-specific primers of Coxsackie A-24 variant (CA24v) and enterovirus-70 (EV-70). EV negative samples were also tested for human adenovirus. Five representative CA24v-positive samples were subjected to partial sequencing and phylogenetic analysis.

Results: Thirty-three AHC patient samples were included in the testing and analysis. EV was detected among 54.5 % (18/33) of the patients and all were found to be CA24v, while no EV-70 or human adenovirus was detected. Partial 3C-proteinase sequencing revealed that the CA24v strains from Kalburgi were closely clustered and had 99 % sequence identity with CA24v strains reported from China in 2023. However, the Kalburagi strains were 90.3-93.2 % identical to previously reported Indian strains.

Conclusion: To summarize, CA24v was identified as an etiological agent responsible for the recent acute hemorrhagic conjunctivitis outbreak in Kalburgi. The CA24v strain detected was closely related to the currently circulating Asian strains.