Thousands of school students competing at national sports tournaments this week could spread mumps around the country, an immunisation expert says.
At least three tournament organisers - for rowing, volleyball and waka ama - say they have not received warnings or advice about the mumps, which is at epidemic levels in Auckland.
The Auckland University Immunisation Advisory Centre's Nikki Turner said health authorities needed to take more responsibility.
She said mumps travelled easily through teenagers, who were sociable and already had low rates of immunity.
"People can have mumps and have not symptoms. It's highly feasible that teenagers, adolescents, will go to these big tournaments and mix and spread mumps to others. I would expect that to be highly likely."
Ms Turner said teenagers were at particular risk of contracting mumps because they were part of a group of New Zealanders with low rates of immunity.
The Ministry of Education says the only health information it provides to schools is at the request of the district health board or Ministry of Health.
RNZ asked the Health Ministry whether it was its job to issue mumps advice to school tournaments and why none had been given.
In a brief written reply, the Ministry said it did not routinely collect information about such events and its approach is to raise awareness about the disease and the importance of receiving two doses of the MMR vaccine.
The Auckland Regional Public Health Service said it did issue advice to Auckland schools for the recent Polyfest cultural festival held in the area.
Ms Turner said everyone in the health sector needed to take more responsibility.
The number of notified mumps cases in Auckland stands at 1204, with small pockets recorded in most other centres.
Auckland public health authorities say the rate does appear to be slowing as more people become immune through vaccination or exposure to the virus.