DENVER (AP) — Denver-area health officials say four Coloradans have been diagnosed with the West Nile virus.

The Tri-County Health Department said Friday all four patients in Adams, Arapahoe and Douglas counties were hospitalized. They are believed to be the first cases diagnosed in Colorado this year.

The Centers for Disease Control and Prevention say more than 1,100 cases have been reported in the United States in 2012. That’s the highest number of cases reported by this time of the season since the virus was first detected in the United States in 1999.

Most people infected with West Nile virus won’t get sick, but about one in 150 people will develop the severe form of the illness. Symptoms include headache, high fever, neck stiffness, disorientation, coma, tremors, convulsions, muscle weakness and paralysis.

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