A measles epidemic could hit Hawke's Bay after a child from outside the region visited public places in Napier with the highly-contagious disease, including the National Aquarium on June 9 between 10am and noon.
Measles can be life threatening - about 1 in 10 people contracting the disease need hospital treatment.
It can lead to complications including: permanent hearing loss, diarrhoea, pneumonia, seizures and in rare cases swelling of the brain causing permanent brain damage or death.
Hawke's Bay District Health Board's medical officer of health, Rachel Eyre, said measles was a very infectious disease and anyone not immune was at risk if they have come into contact with a person who has the disease.
It spreads via minute breath droplets from breathing, coughing and sneezing and is contagious from before symptoms begin until about five days after onset of a symptomatic rash.