Atlanta ? The nation is on pace to have its worst West Nile virus season in years, federal health officials said Thursday.

So far this year, there have been nearly four times as many cases reported as there were at the same time last year. However, cool weather in August or September – when the bulk of West Nile cases usually occur – could take the sting out of the season, officials added.

Nineteen states, most of them west of the Mississippi, have reported 122 human cases of the mosquito-borne disease. That total includes three deaths.