Missouri Reports Highest West Nile Virus Activity in Years

Jefferson City, Mo. (KFMO) - Missouri is experiencing its highest level of West Nile Virus activity in several years, with health officials warning residents to take precautions as mosquito season lingers longer than usual.

A growing number of blood donors are testing positive for the virus. Missouri is among the most affected states this year, with hospitalizations and deaths running 30 to 40 percent higher than expected nationally. Experts say the warm, wet weather this fall is a key factor behind the surge. The unusually warm October temperatures and sufficient rainfall, in some parts of the country, have prolonged the mosquito season and increased breeding, leading to more opportunities for transmission.

Health officials are urging Missourians to protect themselves by avoiding peak mosquito hours, wearing long clothing, and using insect repellent. Prevention is especially important since there is no specific treatment or vaccine for West Nile Virus.

Missouri typically reports around 17 cases of West Nile Virus each year. So far in 2025, the state has confirmed 21 cases, including three deaths.