Re-emergence of a coxsackievirus A24 variant causing acute hemorrhagic conjunctivitis in Brazil from 2017 to 2018

A large outbreak (over 200,000 cases) of acute hemorrhagic conjunctivitis (AHC) took place in Brazil during the summer of 2017/2018, seven years after a nationwide epidemic, which occurred in 2011. To identify the etiological agent, 80 conjunctival swabs from patients with a clinical presentation suggestive of AHC were analyzed at the national enterovirus laboratory. Real-time RT-PCR for human enteroviruses was performed, and enterovirus RNA was detected in 91.25% (73/80) of the specimens. Twenty-nine swab fluids were used to inoculate cell cultures (RD and Hep2C), and 72.4% (21/29) yielded a cytopathic effect. Genotype IV coxsackievirus A24v (CV-A24v) was identified as the causative agent of the outbreak. Phylogenetic analysis based on the VP1 gene revealed that Brazilian isolates were genetically related to strains that caused an outbreak in French Guiana in 2017. Our results show the re-emergence of CV-A24v causing AHC outbreaks in Brazil between the end of 2017 and the beginning of 2018.