Measles: Which areas are at risk?
25 April 2013 Last updated at 17:58 BST
Cases of measles are on the rise in England. In the first three months of this year nearly 600 people have been reported as having the disease.
This compares with 261 cases for the same period in 2012.
Outside of the outbreak in Wales, the North West and the North East of England are the most affected - both have over 170 cases.
BBC medical correspondent Fergus Walsh goes through the new figures and explains why the highly infectious virus is on the rise.