New Delhi, Aug. 26 -- Two unvaccinated Pennsylvania residents have died after being infected with measles, the first U.S. deaths this year related to the contagious virus.

State health officials announced the deaths Tuesday. They did not reveal any details about the people who died, other than that they lived in Lancaster County, west of Philadelphia.

"My deepest sympathies are with the loved ones who are facing this unimaginable loss," said state Health Secretary Dr. Debra Bogen. "Because measles was largely eliminated in the Commonwealth for more than three decades, people are not familiar with this disease and don't fully understand the potential severity of the illness."

The U.S. has now seen five measles-associated deaths in the l...