Five suspected cases were reported among pupils at Denbigh High School on Friday.

We have seen outbreaks of mumps throughout the country before but we've only had a handful of cases in north Wales since 1994

Dr Richard Roberts

North Wales Health Authority have said they will not be able to confirm the suspected outbreak for two - three weeks.

There have only been a total of five other cases of mumps in the authority area since the introduction of the combined measles, mumps and rubella (MMR) vaccine eight years ago.

This latest suspected outbreak follows recent confirmed outbreaks of the more serious measles in London and northern England.

Uptake of the controversial vaccination has fallen across the UK amid fears - so far unproven - of links between the vaccine and bowel disease and autism in children.

The cases we are dealing with will be off school until they're well but the vaccine offers good protection

Dr Richard Roberts

Earlier this week the North Wales Health Authority revealed the number of children being given the MMR vaccine had fallen because parents were concerned about the possible side effects.

Dr Richard Roberts, consultant in the authority's public health department, said: "We have seen outbreaks of mumps throughout the country before, but we've only had a handful of cases in north Wales since 1994."

Health officials have urged pupils, who have not yet had the full two doses of the MMR vaccine, to have the full dose as soon as possible.

They say it is quite safe for three doses to be given.

Seldom Serious

A team from the authority will visit the school on Tuesday to offer the vaccination.

Parents have been reassured that concerns of a link between the MMR vaccine and autism are irrelevant in this situation because autism never appears in older children.

The second MMR vaccine was introduced 8 years ago.

One vaccine of MMR provides 90% protection against mumps but two doses would provide 99% protection against mumps, measles and rubella.

Mumps usually causes fever and swelling of the saliva glands beneath the ear and gets better within seven to 10 days.

"Although mumps is seldom serious, it can be unpleasant," said Dr Roberts.

He added: "The cases we are dealing with will be off school until they're well but the vaccine offers good protection."