The West Nile virus has killed two more Illinois residents, pushing the state's death total to 13, the most in the nation, health officials said Wednesday.

Laboratory tests have confirmed that more than 1,200 people have been infected with the virus from coast to coast, including one case in California, according to the Centers for Disease Control and Prevention.

If the two latest Illinois fatalities are confirmed by the CDC, the national death toll would be at least 48.

The state's public health department said the new deaths were an 81-year-old woman from southern Cook County, in the Chicago area, who died Sept. 1 and a 76-year-old man from Madison County, near St. Louis, Mo., who died Sept. 5.

The department reported 22 new laboratory-positive human cases of the mosquito-borne disease, bringing Illinois' total this year to 314.

Louisiana is second with 222 confirmed illnesses and 10 deaths, the CDC says.

Health officials say most people who get infected with West Nile virus have either no symptoms or mild symptoms, but a few individuals -- especially the elderly -- can develop a more severe form of the disease.