Cases of measles in the Abertawe Bro Morgannwg, Hywel Dda and Powys health board areas have now risen to 1,039, an increase of 28 since Tuesday.
85 people have been hospitalised, says Public Health Wales.
Across the whole of Wales, 1,170 cases have been reported.
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.