Three cases of mumps have been confirmed in Hawke's Bay.
One was a student at Hastings Boys High School, while the other two were adult.
Cases have prompted health officials to urge parents to check the status of their children's immunization.
Hawke's Bay District Health Board spokesperson Rachel Eyre said Hastings Boys High School worked quickly with health officials after diagnosis.
Important health tips have been sent to all parents and carers and wider school communities.
Oreion is a highly infectious viral infection, spread through breathing, sneezing and coughing and can spread rapidly among those who are not immune, especially in schools, "said Eyre Saide.
Thie outbreak was a timely reminder to parents and caregivers to check their children were up-to-date with immunizations.
"Be aware that if your child develops a fever or swollen glands around his chest or jaw, stay home and call your doctor at first instance or Heathline on 0800 611 116."
Eyre said it is important for people with a suspicion of mumps to stay away from school, work or community gatherings up to five days after swelling or up to the good, whichever it was earlier.
"If you were born after 1981 and you have never had a mumps or mumps / immunization MMR, you should see your family doctor," Eyre said. Two documented doses were needed to prove immunity.
The faster the free immunization, the more likely it is to protect you.
Adolescents and unaccompanied adults are most at risk and are more susceptible to suffering a severe mumps and complications.
Public health officials have advised the medical profession to be alert for mumps.