(AP) — A Scotts Bluff County man has been diagnosed with having West Nile virus — one of four human cases confirmed by state health officials in Nebraska this year.

Scotts Bluff County health officials say that the man is between the ages of 26 and 50. Officials will not reveal his name or residency to protect his identity.

August and September are the peak months for transmission of the mosquito-borne virus.

Officials say that most people who are infected have no symptoms, or experience mild flu-like symptoms. The most vulnerable people are those over 50 or who have weakened immune systems.

There has also been confirmed cases of the virus in Knox, Hamilton and Douglas Counties this year.