More than 330 cases of measles have been reported in the first three months of 2011 - similar to the whole of last year.
Data from the Health Protection Agency (HPA) revealed 334 confirmed cases of measles to the end of April in England and Wales, compared with 374 in all of 2010.
Small outbreaks have been noted in universities, schools and within individual families while some people caught the disease abroad as Europe faced a surge in measles cases.
In mid-April, the World Health Organisation (WHO) warned of more than 6,500 cases of measles in 33 countries, with France being worst hit with almost 5,000 cases.
In England and Wales, the under-25s were most affected in the first three months of the year. The vast majority had not had the vaccine against the disease.
Most cases occurred in London and the South East, followed by Yorkshire and the Humber.
Dr Mary Ramsay, head of the HPA's immunisation department, said: "We again are reminding parents and young adults of the importance of immunisation.
"Although MMR coverage has improved over the last few years, we cannot stress enough that measles is serious and, in some cases, it can be fatal.
"Measles is a highly-infectious and potentially-dangerous illness which spreads very easily.
"Whether you stay here in the UK or travel abroad, it is crucial that individuals who may be at risk are fully immunised."
The most recent UK figures for uptake of the measles, mumps and rubella (MMR) jab, covering September to December 2010, showed 89.4% of children had received their first dose by the age of two.
By age five, 84.8% of children had received their second dose.
Both are slightly up on previous figures.
In the US, health officials have reported 118 cases of measles so far this year - the highest number so early in the year since 1996.
Cases were seen in 23 states. None of the patients died, but about 40% were admitted to hospital.
The US normally sees about 50 cases of measles in a year.
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