Federal health officials are warning Americans that the West Nile virus season has arrived earlier and more aggressively than it has in more than two decades. As of June 30, 2026, the Centers for Disease Control and Prevention confirmed at least 48 West Nile virus cases across 23 states — nearly five times the historical average of about 10 cases by the end of June.
Of those 48 cases, 38 are classified as neuroinvasive disease: the severe form in which the virus penetrates the brain or spinal cord, causing encephalitis, meningitis, or acute flaccid myelitis. Four deaths have already been reported — all in Arizona — making this the deadliest start to a West Nile season in recent years.
