A 15-year-old Freyberg High School pupil is in isolation in Palmerston North Hospital after contracting tuberculosis, and others he has been in contact with could be tested for the contagious disease.

It is not yet clear how, when or where the year 11 student contracted the infection.

"I wouldn't like to speculate on that," said MidCentral medical officer of health Dr Robert Weir.

He was concerned that any more information other than age and sex of the student would reveal his identity.

Students' parents were notified yesterday via email and advised that testing of the infected student's immediate contacts would start later in the term.

Dr Weir said testing sooner than that could give false negative results, as the disease was slow to progress.

There was no danger in waiting that long.

"We are holding off on testing the initial people in the school until late June because we don't want to miss anyone."

He said the boy's family and people who visited the house had had blood tests and classmates would be next for the blood test called Quantiferon Gold.

He said testing the entire school was unlikely.

Extending the tests to pupils would depend on the results of the family tests.

"If those are clear there is no need to test further.

"We start with people with the highest level of exposure first and if we find positive tests then we go down to the next level of exposure."

Dr Weir said there was no cause for alarm.

Testing would reveal if anyone had latent TB, the precursor to the infectious active TB which could take up to two years or more to develop.

People infected are prescribed a combination of antibiotics over several months.

"Anyone testing positive for latent TB will be assessed further and may be asked for further testing and be seen by a specialist who will decide if it's appropriate to use antibiotics."

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 and 14 students at the school being treated for TB.

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

From 2001 to 2005, there were 48 cases notified in the district and Dr Weir said that MidCentral had seen 13 cases of TB in the past year.

Freyberg principal Peter Brooks said the student was the only one so far who had been diagnosed and he wanted to protect his identity for fear of repercussions on his family.

"It wouldn't be hard to identify him if people had a few details."

A meeting for parents has been scheduled for 7.30pm on May 31 at the school.

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

SYMPTOMS

The symptoms of tuberculosis include a persistent cough with phlegm (sometimes containing blood), which doesn't go away with usual antibiotic treatment. There can also be weight loss, and sweats, especially at night. Anyone with these symptoms should see a doctor as soon as possible for further assessment. Only TB disease involving the lungs is considered infectious to others. The TB bacteria are passed on via coughing and close contact. The risk is highest for people who live in the same household as the infectious person and the risk is very low for people who have shorter periods of contact with the case.People infected are prescribed a combination of antibiotics over several months.

- © Fairfax NZ News