The state health department has raised the number of cases of West Nile virus recorded in Iowa. Nineteen human cases of the mosquito-borne illness have been added to this year’s tally, in a dozen counties. It brings the total number of cases of the illness to 98 this year. State investigators have confirmed the germ in animals, humans or insects in 87 counties this summer and three people have died of the disease, which is the newest of several forms of mosquito-borne encephalitis. The virus is carried by one species of mosquito, and isn’t transmitted in any other way. So once a freeze kills the summer bugs, there will be no more risk of West Nile for this year. State epidemiologist Patricia Quinlisk says while a hard frost is possible this week, it may not come in all parts of the state and she urges folks to keep using Deet-based repellents and covering up to ward off mosquito bites.