Public Health Wales is investigating three confirmed cases.
People who visited particular areas of Rhyl are being warned to be alert to the signs and symptoms of measles after a local cluster of cases.
Public Health Wales is investigating three confirmed cases of the infection, and two related suspected cases.
Among the cases are people who spent time in healthcare waiting rooms and at a cinema and fast food restaurant in Rhyl while they were contagious, so that the infection may have spread.
Measles is very contagious and spreads easily to people who are not vaccinated. Public Health Wales is warning people to be vigilant if they were in any of the following places:
· The Vue cinema in Rhyl on the afternoon of Saturday 29 June
· The McDonalds restaurant on Rhyl high street on the afternoon of Saturday 29 June
· The accident and emergency department/GP out of hours waiting room at Ysbyty Glan Clwyd on the evening of Thursday 20 June, the morning of Sunday 30 June or the evening of Sunday 30 June
Anyone who may have been exposed to measles at these locations who was born after 1970 and has not previously had measles, is advised to check that they are fully vaccinated with two doses of MMR, and should be vigilant to the symptoms of measles.
These include a high temperature, cough, runny nose, red eyes (conjunctivitis), and a distinctive red rash, which commences on the back of the head, spreading to the face and onwards, down the body. The rash typically appears three to five days after onset of symptoms.
Anyone who suspects they or their child has measles should contact their GP or NHS Direct Wales on 0845 46 47. They should alert their health care providers of the symptoms before attending any appointment.
People with symptoms should stay home from school, nurseries and social events such as holiday clubs, festivals and birthday parties.
Measles is highly infectious and the only way to prevent large outbreaks is through vaccination.
Parents of a local primary school, Ysgol Clawdd Offa in Prestatyn, have been directly advised of the signs and symptoms of measles as one of the cases under investigation has been at the school while infectious.
Dr Chris Johnson, Consultant in Health Protection, said: “At present, we are not investigating an outbreak of measles, as there is no evidence that measles has spread beyond one closely linked group of people.
“However, we are very aware that measles spreads quickly and easily between unvaccinated people and we do have concerns that others may have been exposed to the infection at the cinema or healthcare waiting rooms last weekend.
"At all times, we advise anyone who has not been fully vaccinated with two doses of MMR to ensure they are protected against measles, which can be very serious and potentially fatal.
"With summer holidays coming up, and people attending large events and holidaying in countries where measles is common, we would especially urge everyone to ensure they and their children have received the MMR vaccine."
The first dose of MMR is usually given to babies at between 12 and 13 months of age, and the second at three years and four months of age, but it is never too late to catch up on missed doses.
About one in five children with measles can experience serious complications such as ear infections, pneumonia or meningitis. One in 10 children with measles ends up in hospital and in rare cases it can be fatal.