Public health officials are worried about a possible Measles outbreak on Martha’s Vineyard after an unvaccinated child was diagnosed with the disease last week:

“While the child was immediately identified and subsequently isolated from the community, we know that individuals on the island were exposed to the virus during a phase of the illness in which the patient is infectious but has no symptoms,” the hospital said in a statement.

Measles can be very contagious to children and adults who are not vaccinated against it. Symptoms are similar to a cold at first, but a red blotchy rash soon appears.

Anyone who thinks they might have measles should call their doctor first instead of going directly to a doctor’s office or a hospital.

Although the child was visiting Martha’s Vineyard from abroad, this case is likely in keeping with findings from earlier this month, that anti-vaccine parents tend to cluster in rich, white areas.