People who went to the Armageddon Expo at Claudelands Event Centre last Sunday are advised to monitor themselves for signs and symptoms of measles.
A person who went to the expo has been confirmed to have measles which may have spread to other people.
The case was well but would have been infectious at the time of the event, said Waikato District Health Board medical officer of health Dr Anita Bell.
"Those who attended the event on Sunday need to be mindful of the signs and symptoms of measles within the next few weeks," she said.
Measles is spread by tiny droplets in the air and is one of the few diseases that can spread so easily to those nearby.
Dr Bell said anyone displaying symptoms of measles, which include fever, cough, blocked nose, sore red eyes, should immediately telephone their doctor or Healthline on 0800 611 116 for advice.
"It's a timely reminder to everyone else to check that they and their children are fully immunised against measles."
Anyone who attended the event on Sunday should check if they are not immune to measles.
People who are regarded as not immune to measles are:
- People younger than 45-years-old, born after January 1, 1969, who have not had two doses of the measles-mumps-rubella (MMR) vaccine or have not had a laboratory confirmed positive measles result
- Children over 4-years-old who have not received their second dose of MMR
- Infants under the age of 15 months who have not received their first routine dose of MMR vaccine. They are susceptible and rely on everyone else to be immune so that measles does not spread to them
"Measles can be a very serious illness, with one in three sufferers experiencing complications such as ear infections, pneumonia, bronchitis or diarrhoea," said Dr Bell.
"While one in 10 on average requires hospitalisation, admission rates in this outbreak have been higher."
Dr Bell said immunisation is the best protection from this potentially serious disease.
"Immunisation protects not only the individual, but also blocks the spread of this disease within our communities."
Anyone born before 1969 or who has received two doses of MMR can reasonably assume they are already immune.
If families suspect someone has measles they should call their doctor, where possible, before visiting to avoid spreading the disease while waiting.