One man may have unwittingly exposed hundreds to measles in Lower Hutt

Regional Public Health has confirmed the Wellington region's fourth case of the disease.

Medical officer of health Dr Annette Nesdale says a man, who didn't realise he was infectious, visited a number of Lower Hutt businesses last Friday afternoon.

These include Pete's Emporium, Pak n Save, Animates and the BP petrol station at Melling.

She says he was also at a party on Saturday night, with about 80 others.

Dr Nesdale says anyone younger than 50, and unvaccinated, who came into contact with the man is at risk of developing measles.