The measles epidemic which is endangering hundreds of children in Wales shows no sign of ending.
This follows a 25% rise in the new cases reported over Easter.
The south Wales outbreak has prompted health officials to stress again the vital need for parents to ensure their children have the MMR jab.
Officials renewed their appeal as the number of confirmed cases hit 541.
Health experts, who announced that 109 new cases were reported in the last week, repeated warnings that the contagious virus is a potential killer.
The Swansea-centred measles epidemic has emphasised the need for thousands of unvaccinated children to have proven protection by getting the MMR jab.
But there are increasing worries that these pleas are not being acted on in the wake of a virus spreading "at an alarming rate".
Public Health Wales (PHW) is concerned that take-up of the vital vaccination is far too slow, putting lives at risk.
Dr Marion Lyons, PHW director of health protection, said that measles can leave unprotected children brain-damaged or dead and cannot be taken lightly.
That's because, she said, you can never tell who will go on to develop the more serious complications of pneumonia or inflammation of the brain, with MMR jabs offering the only protection against these.
Ms Lyons added: "We are starting to see parents bringing unprotected children to get vaccinated, showing that they're taking the outbreak seriously and have confidence in the jab as the best way of protecting children."
Copyright Press Association 2013