The World Health Organisation has warned the disease is spreading across Europe wherever immunisation coverage has dropped. The largest outbreaks have been in Italy, with over 200 cases in January alone, and Romania, with more than 3,400 cases and 17 deaths since January last year.

In Portugal, one of the cases is in the north and four are in the Algarve, the latter all arising in March.

One of the cases is known to have come from Venezuela, but the others are still being investigated.