As of Friday, the Pennsylvania Department of Health reported nine cases of West Nile virus in Pennsylvania residents, including one in Philadelphia, one in Bucks County, and two in Delaware County.

Jeff Moran, a spokesman for the Philadelphia Department of Public Health, said the Philadelphia case is a city resident who was diagnosed in Maine and is being treated in a hospital there.

The New Jersey Department of Health and Human Services reported four human cases, one each in Hudson, Ocean, Middlesex, and Monmouth Counties. The Monmouth case was exposed in Ocean County and the case in Hudson was exposed out of state.

People get West Nile virus from mosquitoes, who get it from infected birds. Many people get no symptoms at all, but the disease can be fatal. Texas has been particularly hard-hit this year. - Stacey Burling