Northland health authorities are warning of a mumps outbreak in Dargaville.
Northland District Health Board said there were eight cases in the Northland town, making a total of 24 in the region this year: four times last year's numbers.
The DHB said that with school holidays coming up and the mumps outbreak in Auckland, it was important for Northland people under the age of 35 to be vaccinated.
Mumps causes swelling in the glands around the face and can lead to meningitis in about 1 in 10 people.
In rare cases it can cause sterility in boys past puberty.
The DHB said there had also been a big rise in whooping cough cases in the north with 48 notifications this year compared to nine in 2016.
Of those, 25 - including a baby who was admitted to hospital - came from the beach community of Ngunguru near Whangarei.