A hard measles outbreak previously limited to Davis County now has spread to adjacent Weber County, the Weber-Morgan Health Department confirms.

A 32-year-old woman has been hospitalized with the disease, which was first detected two weeks ago in Davis County, said Weber Health Director Mark Nichols.The woman was exposed to the airborne virus in Davis County, Nichols said. He added that his agency is trying to locate people in Weber County with whom the woman had contact in the past two weeks.

Hard measles is not caused by the same virus as rubella or German measles, which can cause birth defects if contracted by pregnant women.

The Davis County Health Department has confirmed 45 cases of measles.

Nichols said people, excluding infants younger than 15 months, without well-documented history of measles immunization should be immunized.

People born prior to 1957 are most likely immune because they were exposed to natural measles when there were millions of cases in the late 1950s and early 1960s, he said.