Doctors last night warned that the crisis of mumps among teenagers and people in their early 20s had reached national epidemic proportions, at 15 times the rate a year ago.
Nearly 28,500 suspected cases of mumps were reported in England and Wales in the first 17 weeks of the year, compared with 1,800 in the same period in 2004.
The scale of the crisis was revealed by the Health Protection Agency last night as doctors warned that the the illness could spread to younger children because of the low incidence of baby immunisation via the MMR vaccine in some parts of the country.
The huge acceleration in a disease that can be particularly painful in young people comes despite repeated appeals for universities, army bases and other institutions to inoculate their populations against the disease.
Most cases are from the generation that missed the introduction of the combined measles, mumps and rubella jab in 1988. Before that, there were no mumps vaccines - meaning there were routine outbreaks, with as many as 1,200 people being admitted to hospital in a year.
The Department of Health said it had alerted GPs to the risks posed by mumps among young adults and recommended that "every effort should be made" to ensure all children were fully immunised.
Some higher education in stitutions had offered special inoculation sessions to protect young people. "In order to limit the spread of mumps in the UK, we recommend that all at-risk school leavers and other young adults who have not received MMR, or only received one dose, should ensure they take up the offer of MMR vaccination."
Last year only about 3% of confirmed cases were among children under 12. But there are increasing fears that the consequences of the repeated scares over the measles part of MMR, with what the government insists are unfounded fears over a link to autism, may mean that measles and mumps make a potentially dangerous return in school-age children too.
A huge MMR catch-up campaign is being completed in London primary schools, because in parts of the capital the take-up among infants has slumped to around 60%, far lower than the 95% that experts say is enough to protect communities. Overall, the take-up of the first jab among two-year-olds is around 80%. They should be inoculated again between three and five.
The mumps epidemic has reached such a height that public health officials have given up testing the vast majority of cases in the laboratories using saliva samples. Last year 16,430 suspected cases were reported in all, of which more than 8,100 were confirmed, twice the 3,907 of the previous five years combined. In 1996, there were just 96 confirmed cases.
The disease can be deeply unpleasant because of the risks of complications after puberty. It can lead to inflammation of the testes in young men, and rarely, sterility.
In women, it can lead to swelling of the ovaries and occasionally spontaneous abortion in the first few months of pregnancy.
The Health Protection Agency said all school leavers should be checked to ensure that they had received two doses of the MMR vaccine to provide the necessary protection against the disease.
In an article in the British Medical Journal today, doctors at the Guy's and St Thomas' NHS Foundation Trust and King's College in London, warn that the initial success of MMR in controlling mumps has been compromised.
"Doctors need once again to include mumps in the differential diagnosis of a broad range of conditions in adults and children. This epidemic underlines the importance of ensuring that all children and young adults have received two doses of MMR."
