A Palmerston North campus at the centre of a measles outbreak is in damage control mode with classes shut down, students in quarantine and teachers scrambling to salvage the semester.

Public health authorities were notified of the cases at the International Pacific United tertiary institute by a GP on Saturday. The virus is highly contagious and can cause serious illness or death.

Seven cases were initially confirmed, but by Wednesday one had been taken off the list, MidCentral District Health Board spokesman Jordan Dempster said.

LUCY NICHOLSON A measles vaccine.

The initial figure was overcautious and after all the cases had been through laboratory testing, one was found not to be measles, medical officer of health Dr Rob Weir said.

However, there was still potential for new cases to be identified.

IPU classes are cancelled until next week at the earliest as university officials seek to control the spread of the disease, and students had been asked not to gather in large groups.

The outbreak was creating a headache for IPU academically. It has fallen in the middle of the summer semester, when it is difficult to make up lost class time, community liaison Joe Rush said. "We are currently working through what will happen regarding class content."

The dining hall, library and recreation centre are closed. Hospital staff are working at the campus and a clinic is offering free measles vaccinations.

People confirmed to have measles were stable in quarantine, Dempster said, and those who do not have immunity and had come into contact with them are also in isolation.

"At this stage it is not possible to exclude an overseas origin for the outbreak."

A "variety" of people were sick, but details about whether they include staff or new arrivals to New Zealand could not be confirmed. About 87 per cent of IPU students come from overseas. The institute is now asking all on-campus staff and students to confirm immunity.

Those who have been vaccinated or previously had the disease are immune, while those in New Zealand before 1969 are treated as immune because of the past prevalence of the disease in the community, the Ministry of Health website says.

Measles affects both adults and children, and can not be treated easily once contracted. About one in 10 people who get measles will need hospital treatment and 30 per cent will develop complications, which can also be serious, the ministry says.

"Measles is a very infectious disease, so anyone who is not immune to measles is at risk if they come in to contact with the disease," Weir said. "It is very important that anyone who thinks they may have measles should stay away from work, school or public places."

More than half of children with low immunity, and who contract measles, will die. "The illness usually starts between 10 and 14 days after contact with the measles virus. [It is] contagious from just before symptoms begin, until about five days after onset of the rash," Weir said.

Symptoms include fever, a runny nose, cough, sore red eyes and a rash.

Last year, MidCentral recorded at least 21 cases of measles, including cases that prompted shut downs at Cornerstone Christian School in Palmerston North, and Waiopehu College and Levin Intermediate in Horowhenua.

Between 2004 and 2011, the DHB had no confirmed cases.

Anyone who thinks they may have measles should contact their GP by phone, or call Healthline on 0800 611 116 for advice. More information is available on the MidCentraldhb.govt.nz