The number of confirmed cases of measles in the Dutch Bible belt outbreak has reached 921, the public health institute RIVM said on Thursday.

This is an increase of 141 on a week ago. In addition, a further 21 children have been hospitalised, the RIVM said.

However, the total is a ‘major underestimate’ of the real number of cases because most people do not report their illness to family doctors, the organisation said in its latest update.

Most of those infected are children aged four to 12 who come from families which refuse vaccinations on religious grounds.

The RIVM expects the epidemic to continue until the autumn and to be of the same proportions as the last outbreak in 1999-2000, when 3,000 cases were reported.