A Palmerston North school has confirmed one of its students has contracted the infectious disease tuberculosis.

A year 11 Freyberg High School boy has been diagnosed and is in isolation.

MidCentral medical officer of health Dr Robert Weir said it was hard to determine how far the disease had progressed and that a testing programme had been started to assess if the infection had been passed on.

Tubercolusis, which typically attacks the lungs, is easily transmitted, however the majority of cases do not develop into infectious disease.

It can be passed on through the air when people who have an active tuberculosis infection cough, sneeze, or otherwise transmit their saliva.

Last year there were 306 cases of active tuberculosis diagnosed in New Zealand, with two of those cases resulting in death, Dr Weir said.

A letter has been sent to Freyberg High School parents via email notifying them of the case.

The letter said the risk of tuberculosis in school contacts was low and the school planned to start blood testing the boy's closest school contacts as a precaution.

Principal Peter Brooks said classmates would be tested in week nine of the school term.

"Testing would be inappropriate before then,'' said Dr Weir.

"Testing too early could give false negative results.''

In 2006 a year 9 student at Palmerston North Boys' High School was admitted to hospital with the infection sparking hundreds of blood tests in the city.

Two other cases were confirmed at Monrad Intermediate and Palmerston North Intermediate Normal at the time after contact with the student.

Dr Weir said MidCentral had seen 14 cases of tuberculosis in the past year.

A meeting for parents has been scheduled for 7.30pm on May 31 in the staff room at Freyberg High School with MidCentral staff to address any concerns.

In the meantime parents are encouraged to phone the Public Health Service on (06) 350 9110 with any queries.

- © Fairfax NZ News