Worries measles is spreading undetected through the country

Three new cases in Manawatu and Nelson were announced yesterday - bringing total current infections to four.

Health New Zealand hasn't been able to confirm how each became infected - and is warning of a potential national outbreak

Immunisation Advisory Centre Medical Director, Nikki Turner, says four cases mightn't sound scary - but measles is highly infectious.

She says it's hard to know where these cases come from if not from travel - and we don't want it spreading through the community.