The number of cases of measles in the Dutch Bible belt has gone up around 40% to 230 over the past week, the public health institute RIVM said on Thursday.

A further two people have been hospitalised, taking the total to six children and one adult. The epidemic has also spread to three more primary schools and one secondary school, the RIVM said.

Fundamentalist Protestants in the Netherlands do not believe in having their children vaccinated. The measles vaccine is given to most children in the BMR combination injection at the age of 14 months and again at nine years.

The total number of cases may be far higher because not everyone will have visited their doctor, the RIVM said. Measles is spread by coughing and sneezing.