Identification of coxsackievirus A-24 GIV C5 strain as the cause of acute hemorrhagic conjunctivitis outbreak in Hyderabad, India in 2022.

Viral infection is frequently the cause for acute hemorrhagic conjunctivitis (AHC) epidemics. AHC can result from adenoviruses, with enterovirus 70 and coxsackievirus A24 being the primary agents. AHC was initially identified in Ghana in 1969, caused by enterovirus 70 and leading to a global pandemic. Since 2000, outbreaks of AHC linked to coxsackievirus A24 variant have been documented in Spain, Pakistan, Singapore, India, Korea, and China. A sudden surge of conjunctivitis cases reported in October 2022 in and out of the Hyderabad region. This infection presented with usual symptoms of redness of the eyes, discharge, pain in the eyes and crusting. Occular swab samples from 110 patients were collected in order to identify and characterize the virus that was causing the epidemic. We examined adenovirus, enterovirus, COVID-19 and Herpes Simplex Virus by using commercially kits available at the hospital. Conserved regions in the enteroviral 5'-UTR and VP2 gene were analyzed further for characterization of serotype at the National apex laboratory. None of them was found positive except Enterovirus in 16.36 % (18/110) of the patients. From enterovirus-positive samples, the coxsackievirus A24 was observed in all 18 positive samples. These clinical isolates constitute a new lineage cluster associated with genotype IV-C5, according to additional sequencing of the full-length VP2 genes and subsequent phylogenetic analysis. In conclusion, the current outbreak of acute haemorrhagic conjunctivitis in Hyderabad, India was traced to the coxsackievirus A24 strain GIV C5.