Health authorities fear the current measles outbreak could spread further, after a staff member at Dunedin Hospital contracted the highly infectious disease.
Otago has now had two cases, both linked to an infectious visitor from Wellington.
The Southern District Health Board says it has made every effort to contact patients and staff with whom the infected health worker had contact early last week.
It is also trying to track down passengers from two Air New Zealand flights between Dunedin and Auckland that the person travelled on last Tuesday and Friday.
The board says the infection was carried south in September by a university student from Wellington.
Wellington has had five confirmed cases of measles since the end of May and Auckland 273.