Maryland officials declared a measles outbreak Monday in Carroll, Cecil and St. Mary’s counties.
The three counties accounted for 26 of 31 confirmed cases of measles in the state this year, health officials said, and all of those 26 cases occurred since July 15.
A single measles case was confirmed in Charles County since July 15.
All 27 measles cases infected unvaccinated Marylanders.
The Maryland Department of Health assured the public that there is no evidence of widespread transmission of measles within the community. Most of the cases resulted from measles spreading within individual households.
Officials did not specify if any cases were related to international travel.
People who have not received the measles, mumps and rubella (MMR) vaccine have a 90% chance of contracting measles if they are exposed.
Getting one scheduled dose of the MMR vaccine is 93% effective at stopping someone from getting measles, while receiving both scheduled doses of the vaccine is 97% effective at preventing someone from contracting measles, according to the Centers for Disease Control and Prevention.
The outbreak since July 15 consisted of 13 cases in St. Mary’s County, eight in Carroll County and five in Cecil County.
Before July 15, Maryland health officials confirmed a total of four cases in Anne Arundel, Baltimore and Prince George’s counties.
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