For the first time in 13 years, the Netherlands has been hit by a serious outbreak of potentially deadly measles. The outbreak is concentrated in the country’s extensive Bible Belt, where the majority of fundamentalist Protestants do not believe in having their children vaccinated.

More than 30 cases have so far been reported, but the public health institute, RIVM, says that “in view of the low vaccination uptake in the Bible Belt, it is assumed that the illness will spread further among unvaccinated children in the near future”.

In fact, the figure of 30 could already be a significant underestimate, acknowledges the RIVM. Given the reluctance of most of the ultra-conservative population to put their faith in medicine, not everyone who has become ill will have visited the family doctor.

This poses a problem, the institute says, because it means the health authorities cannot form an accurate picture of the extent of the illness – which is highly infectious and spread by coughing and sneezing – until it has become a well-established threat.

The Dutch government has begun a public information campaign hoping to avoid a repeat of the last major outbreak of the virus in the same area between 1999 and 2000, in which three children died, 150 were admitted to hospital with complications and 3,300 were infected.

It has already been established locally that the new outbreak is so far clustered around a number of schools run by the Dutch Reformed Church, which objects in principle to vaccination.

“The belief is that medical intervention is against the will of God”, says Prof Roel Coutinho, director of the RIVM’s Centre for Infectious Disease Control.

“We have had a debate in the Netherlands about mandatory vaccination but it is not practical. Many people would rather go to jail than be vaccinated.

“So, essentially, we expect this outbreak to spread again very much as in 1999 – from schools to meetings and other social occasions.

“The problem is that we are talking about several thousand unvaccinated children currently at risk of getting measles – and one sick child can infect 10 more.”

Overall, the Netherlands has an impressive 96 per cent uptake of the measles, mumps and rubella (MMR) vaccine for babies over 14 months.

However, in some primary schools in the Bible Belt – in which some 360 traditional “black-stocking” churches have about 650,000 members – just 2 per cent of children receive the MMR jab.