A staff member at Les Mills Auckland City has been diagnosed with measles.
They attended Les Mills Auckland City on Tuesday October 8.
Anyone who attended the gym since Sunday October 6 is urged to contact their doctor or call Healthline on 0800 611 116 if they suspect any illness.
Measles is an airborne disease which spreads easily through the air via coughing and sneezing.
Les Mills is contacting those who had close contact with the staff member.
New Zealand has experienced an outbreak of the disease this year, with 1808 confirmed cases so far - 1471 of those cases were in the Auckland region.