CBS News’ chief medical correspondent, Dr. Jonathan LaPook, wrote in a social media post that he spoke Saturday with Fauci, who said he was likely infected from a mosquito bite that he got in his backyard.

There are no vaccines to prevent West Nile, or medicines to treat it. As of Aug. 20, the CDC had recorded 216 cases in 33 states this year. It’s best prevented by avoiding mosquito bites.

would be challenging to avoid all mosquito bites

https://www.epa.gov/insect-repellents/tips-prevent-mosquito-bites