Public Health Wales says there are now cases of measles in every health board area in Wales.
Dr Marion Lyons, Director of Health Protection, says "we have no way of knowing where the outbreak might spread."
We can’t bring this outbreak to an end unless the parents of unvaccinated children either arrange vaccination with their GP, call into one of the weekend drop-in sessions or ensure that if their child attends a school where vaccinations are being offered, they have signed a consent form for them to be vaccinated.
As children return to school after the Easter holidays, the opportunities for measles to spread increase. Now is the time to vaccinate your children.
2013 is expected to be the worst year for measles in the UK for the past two decades. Read more about the illness and how it is treated.
If the Government's top adviser on immunisation thinks the risk of an emergency in England is a possibility, I believe him.