Figures published later today are expected to show a further increase in measles cases as children have gone back to school after Easter.
Doctors are urging people to get their kids vaccinated, as a second outbreak has emerged in the North East of England where there are already more than 200 cases.
There are fears the disease could spread across the country.
Last week 25-year-old Gareth Williams died, although he had measles, it has not been confirmed whether the disease was the cause.
A man who died in from a suspected case of measles in Wales was infected with the disease at the time of his death, health officials said.
A mother convinced the MMR vaccine led to her son's autism has not immunised her daughter, despite the link being disproved.