Incidence of rubella - which public health specialists believe is near eradication in the UK - shot up in 1996.

The outbreak, mainly in young men, is thought to have led to a sharp increase in the number of babies suffering birth defects in that year.

Public health specialists fear that media reports of side effects associated with the MMR jab have made parents reluctant to get their children vaccinated - meaning the infection is more widely present in the community.

Rising incidence

A report in the British Medical Journal examines incidence of the disease since vaccination was introduced to the UK in 1970.

Then only schoolgirls and women at heightened risk were included in the programme.

Since then it has expanded to include all infants.

Figures from the national congenital rubella surveillance unit show that the programme has been a success.

The number of babies suffering birth defects as a result of rubella infection has fallen from 200 to 300 a year before 1970 to an average of four between 1991 and 1995.

In the first years of the programme, 1971 to 1975, the figure was 48.

The authors say these figures show both the immediate and continuing impact of the vaccination programme.

However, fears about the safety of the combined MMR vaccine were publicised in 1995.

The report says this reduced uptake of the vaccine, resulting in a resurgence of the disease - in 1996 12 babies were born with rubella-related birth defects.

Devastating birth defects

Rubella is a mild disease in children, but if they infect a pregnant woman it can have severe effects on the unborn child.

Vaccination aims to protect pregnant women

Professor Catherine Peckham, of the Institute of Child Health in London, is one of the report's authors.

She described the effects of rubella on an unborn child as "devastating".

"Rubella is very serious if it occurs in pregnancy. That's why in the past there were a lot of children born with very severe deafness, blindness, heart defects or mental retardation," she said.

"But vaccines have prevented that - we know that from the epidemics we've seen in the past."

She said the key to ensuring there were as few cases as possible was mass vaccination.

"You're preventing the growth of the reservoir of infection in the community so that women who are susceptible won't be exposed."

Vaccine risks

However, some parents do not trust the current vaccination programme, which recommends that one-year-olds get a combined jab for measles, mumps and rubella.

Evidence published in The Lancet medical journal suggests that the combined jab may cause autism and Crohn's disease.

Autism is a neurological disorder that affects the functioning of the brain and Crohn's disease affects the bowels.

But most doctors say that such risks are minimal, and certainly lower than the potential risks of a measles, mumps or rubella infection.

Parents have also expressed fears that a three-in-one vaccination is too powerful for a one-year-old and could have damaging side effects.

Some pharmacists have addressed these concerns by importing individual vaccines for each disease.

But Professor Peckham warned that parents who opt for single jabs often focus on the measles risk and may leave out rubella vaccination, particularly for boys.

The results of this could undo the good of the vaccination programme, she said.