Pediatric Meningoencephalitis Cluster Caused by Snowshoe Hare Virus, Whistler, British Columbia, Canada, 2024

Snowshoe hare virus (SSHV) is an arbovirus in the California serogroup known to circulate throughout Canada and northern latitudes of the United States. The clinical spectrum of SSHV infection ranges from asymptomatic or mild febrile illness to neuroinvasive disease; neuroinvasive disease occurs more often in children and young adults. We describe a cluster of confirmed and probable SSHV meningoencephalitis cases in 3 children from Whistler, British Columbia, Canada, in the summer of 2024. We highlight the shared epidemiology, clinical manifestations, serologic diagnostic methods, and outcomes for the cases. All 3 children acquired the infection locally and made a full recovery. This case series suggests underrecognized SSHV infection prevalence that warrants enhanced surveillance and review of existing diagnostic algorithms. California serogroup viruses, including SSHV, should be recognized as a potential cause of neuroinvasive disease in North America during mosquito season, particularly when initial diagnostic testing is inconclusive.