West Nile Virus Cases Rise Across 39 US States in 2023

The United States is experiencing a significant number of West Nile virus cases in 2025, with at least 771 human cases reported across 39 states, including 490 severe neuroinvasive cases affecting the brain. The virus, primarily transmitted through infected mosquito bites, has been detected in various states such as Louisiana, Connecticut, California, and Texas, prompting health officials to intensify mosquito monitoring and control efforts. While many infected individuals show no symptoms or only mild flu-like symptoms, about 1 in 150 may develop severe neurological complications, particularly older adults and those with weakened immune systems. Climate change is extending mosquito season, increasing the risk of transmission and necessitating ongoing vigilance, including the use of repellents, protective clothing, and elimination of standing water to reduce mosquito breeding grounds. Public health authorities emphasize that there is no specific treatment or vaccine, making prevention critical as the mosquito-borne disease season continues until the first hard frost. Residents in affected areas are urged to take precautions, especially during peak mosquito activity at dawn and dusk.