The number of West Nile virus cases in Arizona continues to grow, making 2021 a record year for cases. As the number of probable and confirmed cases rise, Maricopa County is working on prevention methods. 
Cases of West Nile can range from mild to severe. This year, the number of severe cases is also on the rise.
So what is West Nile virus, and how is it being prevented and researched? 
In this week's episode of Valley 101, a podcast from The Arizona Republic and azcentral.com, producer Alexandra Watts answers questions about West Nile virus in the state and why the number of cases is increasing this year.