The current rate of MMR vaccination uptake in Sunderland is 84%

More than 100 cases of the disease have been reported already this year, compared with 14 in the whole of 2002.

Health officials say the number of cases is expected to rise still further.

The rise has followed a significant drop in the uptake of the triple vaccine against mumps, measles and rubella (MMR) and health officials fear the outbreak could spread to younger children.

Teenagers aged between 14 and 19 have been particularly badly affected, according to the figures released by the South of Tyne Local Health Protection Unit on Monday.

Now that the schools have resumed, young people will be in closer contact with each other and that increases the chances and likelihood of transmission David Tregoning

Current Department of Health guidance recommends two doses of the MMR vaccine between the ages of 13 months and 20 years.

But it is thought but most older children would have either had one dose - as per previous guidance - or missed vaccination completely.

David Tregoning, from the Health Protection Unit in the South of Tyne area, said: "There is not alarm, but there is cause for concern,

"We have had a substantial number of cases of mumps this year, and certainly in the last two months.

"We recognise that mumps, historically, was a disease of winter so we can envisage that the problem might get worse, rather than better, without active intervention.

Second dose

"Now that the schools have resumed, young people will be in closer contact with each other and that increases the chances and likelihood of transmission.

Mr Tregoning said the outbreak was not unique to Sunderland, but urged teenagers to ensure they had a second dose of the vaccination.

He added: "The vast majority of people will get their children vaccinated... but with the current outbreak among teenagers, our concern is that if the illness worsens then it may infect younger children.

"Durham and Northumberland have already been affected by mumps and we will be seeing it in other parts of the country, so we are not unique in any way."