The huge surge in measles cases is due to "ongoing large outbreaks in Europe", according to health chiefs.
More than 400 measles cases confirmed in huge outbreak - find out if your area is affected
More than 400 measles cases have been confirmed across England this year due to a huge outbreak spanning Europe, health officials have said.
Public Health England is urging people to check they are properly vaccinated against the highly infectious viral illness, which can be fatal.
Anyone who has not received two doses of the MMR vaccine is at risk, while young people mixing in close proximity, for example at festivals, are more vulnerable.
Between January 1 and May 9, there have been 440 laboratory-confirmed cases of measles in England.
The total number is already higher than 2017, when there were 267 confirmed cases in England.
In 2016, there were 531 confirmed cases.
How this year's measles diagnoses break down by area...
- London - 164
- South East - 86
- West Midlands - 78
- South West - 42
- West Yorkshire - 37
Dr Mary Ramsay, head of immunisation at PHE, said: "The measles outbreaks we are currently seeing in England are linked to ongoing large outbreaks in Europe.
"The majority of cases we are seeing are in teenagers and young adults who missed out on their MMR vaccine when they were children."
There are currently large outbreaks in Romania and Italy and those travelling to these countries should check health advice beforehand.
Dr Ramsay said: "Anyone who missed out on their MMR vaccine in the past or are unsure if they had two doses should contact their GP practice to catch up.
"This serves as an important reminder for parents to take up the offer of MMR vaccination for their children at one year of age and as a pre-school booster at three years and four months of age.
"We'd also encourage people to ensure they are up to date with their MMR vaccine before travelling to countries with ongoing measles outbreaks."
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