PARENTS are being urged to have their children vaccinated immediately following an increase in measles cases in Wales.

An outbreak has been reported in Ceredigion, health officials have said.

There are said to be 10 cases in the west Wales local authority, and another 20 elsewhere.

Further possible cases are being investigated in Pembrokeshire, Neath Port Talbot, Swansea, Carmarthen, Powys and the old Gwent area.

Public Health Wales (PHW) warned measles can be fatal - particularly for those with underlying medical conditions or children under the age of five.

Dr Roland Salmon, PHW's regional epidemiologist, said: "Many of the cases under investigation had not received their scheduled MMR vaccinations.

"We are urging parents throughout Wales who have not arranged immunisation for their children to act immediately to get them vaccinated.’’ PHW said the latest MMR uptake figures for January to March 2011 show that in Wales, 87% of children reaching their fifth birthday had received two doses of the MMR vaccine.

Coverage ranged from 82% to 94% across Wales.

Dr Richard Roberts, head of PHW's Vaccine Preventable Disease Programme, said as long as there were children who did not receive their MMR vaccinations there was the potential for them to become seriously unwell.

He added: "There is then a danger for the disease to spread to unvaccinated friends, family or others who cannot be vaccinated due to existing health problems and who are therefore highly vulnerable to measles infection.’’ Last week, it was reported that 90% of two-year-old children in the UK had received their first dose of the MMR vaccine - the highest level for 13 years, said the Health Protection Agency.

Children should receive their first dose of the vaccine at 12 to 13 months of age and the second at around three years and four months of age.

Public Health Wales said it was never too late to catch up on missed doses.

Many people who catch measles will have a fever, cough, red eyes and blocked nose, and feel generally unwell.

The blotchy rash appears a few days later, beginning on the face and spreading downwards to the rest of the body over several days.

Dr Roberts added: "If your child is unwell and you suspect it is measles, you should contact your GP. Your child should not attend school or nursery for five days after the rash starts.’’