June 3 (UPI) -- The 981 U.S. measles cases reported by the Centers for Disease Control and Prevention on Monday is an increase by 41 from the previous week.
Twenty-six states have reported cases to the CDC. Outbreaks, defined as three or more cases, currently center in Rockland County, N.Y.; New York City; Michigan; Butte, Los Angeles and Sacramento Counties, Calif.; Georgia; Pennsylvania; Maryland and Washington.
The occurrences are largely linked to travelers who returned from countries with large measles outbreaks, including Israel, Ukraine and the Philippines, the CDC said in a statement on Monday. It added that the majority of those infected in the United States were unvaccinated.
The agency said the virus can spread when people within a community remain unvaccinated, and when people arrive in the United States after contracting the virus abroad.
Measles spread among unvaccinated people in Orthodox Jewish communities in New York State, New York City, and New Jersey after travelers returned from Israel with the virus. As a result, New York City has ordered mandatory vaccinations, and religious leaders have urged their followers to get vaccinated.