Measles cases 'almost double' after outbreaks
There have been almost twice the number of measles cases in England and Wales in the first six months of this year compared with the same period last year, official figures show.
The figure had risen from 497 to 964, the Health Protection Agency said.
There are currently significant measles outbreaks in Merseyside and Sussex.
The agency is urging parents to ensure children are up to date with their measles, mumps and rubella (MMR) vaccinations before the school begins.
Measles can cause serious illness and can, in some cases, be fatal.
Complications can include meningitis and encephalitis - inflammation of the lining of the brain. Rarer disorders of the eye, heart and nervous system can also develop.
Rubella, known as German measles, has also increased, with 57 cases reported between January and June in England and Wales - more than the annual totals for each of the previous nine years.
Most cases are linked to travel to other European countries.
It is usually a mild infection. But if a woman becomes infected in early pregnancy, it can cause birth defects.
Latest data on immunisations across England shows uptake rates of 93% for the first MMR jab and 87% for the second.
In Wales, the figures are 92% and 87%.
The first dose of the MMR vaccine should ideally be given to children between 12 to 13 months of age.
They are given the second dose before they start school, usually between three and five years of age, although it can be given three months after the first.
Dr Mary Ramsay, head of immunisation at the Health Protection Agency, said: "Measles can be very serious and parents should understand the risks associated with the infection, which in severe cases can result in death.
"Although uptake of the MMR has improved in recent years some children do not get vaccinated on time and some older children, who missed out when uptake was lower, have not had a chance to catch up.
"Therefore, there are still enough people who are not protected to allow some large outbreaks to occur among unvaccinated individuals."
She added: "It's vital that children receive both doses of the MMR vaccination and ahead of returning to school after the holidays, we are urging parents to ensure their children have received the two doses, which will provide the best protection against the risks associated with measles, mumps and rubella."
The HPA is advising parents to check with their GP to see if their child has had both doses of MMR.