Clinical and molecular investigation of acute haemorrhagic conjunctivitis outbreak in North India (2023).

PURPOSE: The study aims to investigate an outbreak of acute haemorrhagic conjunctivitis (AHC) reported in North India.

METHODS

All patients presenting to the outpatient clinic department with signs and symptoms (symptoms onset within 36 h) of AHC were enrolled in the study. The conjunctival swab samples were tested for the presence of enteroviruses and adenoviruses. Detailed clinical features of all positive patients were noted. Representative enterovirus-positive samples were sequenced for viral; protein 1 (VP1) gene for type identification. The sequences were analysed by the Basic Local Alignment Search Tool (BLAST) software and enterovirus genotyping tool v1.0. A maximum likelihood tree was constructed using MEGA11.

RESULTS

Out of 133 samples tested, 75.1% (n = 100) samples were positive for enterovirus by real-time PCR. The average duration of onset was 16.9 h. Subconjunctival haemorrhage was observed in 67% of the patients, while 30% of cases had conjunctival chemosis. The causative agent of the current outbreak was identified as Coxsackievirus A24v G-IV. A sequence homology of 96-99% and pairwise distance divergence of 2.9% was observed between study sequences and recent sequences of China outbreak. Mutation analysis showed four common mutations (T281C, A311G, T332C, and T395C) with those of Chinese sequences, however no new mutations were identified in current study sequences, suggesting a close relatedness to CVA24 sequences from China.

CONCLUSIONS

Coxsackievirus A24v continues to be an important agent of Acute Haemorrhagic conjunctivitis in North India. In view of its highly contagious nature, effective and timely public health measures are required to limit its spread.