Three confirmed cases of measles in Rockland County this year have been linked to “international tourists visiting the county.”

The county’s Health Department sent a notification around 4:30 p.m. about the exposure.

“Residents who were exposed to these measles cases have been identified, notified, and are being closely monitored,” it said.

Measles is the most contagious vaccine-preventable viral infection in the world. Throughout the country, 26 states have reported measles cases since the start of the year, including a massive outbreak in South Carolina where officials identified nearly 1,000 cases, mostly among unvaccinated children.

It is the largest outbreak since the Centers for Disease Control and Prevention declared measles eradicated more than 25 years ago.

“Measles and its complications can be severe, but they are preventable,” said Dr. Mary Leahy, Rockland County Department of Health commissioner in prepared remarks. “Vaccination is the single best way to protect yourself and those around you, including infants, toddlers, and people with weakened immune systems. If you are unsure of your immunity, please get vaccinated as soon as possible.”

AP Wire Services contributed to this report.