West Nile virus found in Colorado

LITTLETON, Colo. -- The West Nile virus' westward march has apparently reached Colorado, where health officials reported four animal cases Thursday.

If the cases are confirmed by the Centers for Disease Control and Prevention, Colorado would become the 28th and westernmost state to report the mosquito-borne virus this year.

CDC Director Dr. Julie Gerberding has said birds and mosquitoes could spread the virus all the way to the Pacific Coast. The CDC has confirmed 159 human cases of the disease and nine deaths this year.

Illinois health officials reported three new human cases of the virus, all in the Chicago area. One of the victims, a 70-year-old man, was in critical condition at a hospital.

Colorado health officials said a crow and two horses tested positive for West Nile in Weld County, just south of Cheyenne, Wyo. A third horse was found with the disease in southeastern Colorado.

The virus was first detected in the United States in New York in 1999. Most people who get it see mild flulike symptoms, or no symptoms at all. But it can cause encephalitis, a potentially fatal swelling of the brain, especially in older people and people with weakened immune systems.

Steps to avoid contracting the virus include using mosquito repellent, removing any standing water where mosquitoes can breed and wearing protective clothing.