Another Montgomery County resident has been diagnosed with measles, the state announced Tuesday, raising Pennsylvania’s count to 11 cases in 2026 and the Montgomery County total to three cases.
No new measles cases have been reported in Lancaster County since Friday, when the state Department of Health alerted LNP | LancasterOnline to a seventh case here.
There has also been one case reported in Chester County, and there were two cases associated with out-of-state travelers who visited Montgomery and Chester counties.
All cases occurred among unvaccinated individuals.
The outbreak began in Lancaster County, with the state Department of Health confirming the first cases Feb. 2. Since then, state officials have worked with Cocalico School District and the Lancaster Academy for the Performing Arts to conduct contact tracing.
Measles is a highly contagious disease spread through droplets in the air when a person coughs or sneezes. It can be deadly.
Symptoms of measles infection can take as long as two weeks to develop, which means a person could unwittingly spread the virus without knowing they are infected for that long. Once contact tracing locates an individual who has been in proximity to a measles case, they are notified and advised of steps, like quarantining at home, to break further transmission of the virus.
Measles is 97% preventable with two doses of the measles vaccine, which is safe.
The increase in Lancaster County measles cases is part of a nationwide trend. The federal Centers for Disease Control and Prevention reported that 2,267 measles cases occurred in the U.S. in 2025, more than any other year this century. In 2000, the Pan American Health Organization assigned the United States its measles elimination status, meaning there was not continuous transmission for 12 months. Now the U.S. will likely lose that status.
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