An immigrant from Myanmar who is New Zealand's first case of "extensively" drug-resistant tuberculosis is being treated at a cost of $10,000 a month to taxpayers.

Experts described the case as the most drug-resistant strain reported in New Zealand or Australia.

The man, now in his early 30s, arrived in New Zealand in 2006 with latent TB, but although he had had a chest x-ray, it wasn't picked up until he saw an Otago GP in March last year.

TB usually affects the lungs and is spread by coughing and sneezing, but it can also affect other organs and the lymph glands.

The man went to the GP with a discharge from an enlarged lymph gland on his abdomen.

TB is readily treated by antibiotics, but since the 1980s, drug-resistant bacterial strains have evolved.

They make treatment more complex, expensive and harder for patients to tolerate.

Since 1999, 28 cases of multi-drug resistant TB have been reported in New Zealand, but until Otago doctors detected the present case, there had been none of the even more worrying extensive drug resistance.

Dunedin Hospital respiratory physician Dr Colin Wong and colleagues, writing in the Medical Journal of Australia, said that as well as being New Zealand's first case of extensively drug-resistant TB, it was the most drug-resistant strain reported in Australasia.

"Given the increasing frequency of travel and immigration from high-risk areas, New Zealand and other countries in the region are likely to encounter more cases of extensively drug-resistant TB in the future," the doctors' report said.

The man was initially treated out of hospital. But when preliminary tests showed the strain was unusually resistant "his urgent admission to hospital was arranged, with provision for isolation to prevent airborne disease transmission".

He was put on seven antibiotics - six oral and one injected - some of which had to be imported from the United States after New Zealand supplies ran out.

He is now out of hospital, but will continue to be treated with six oral antibiotics at least until the end of the year.

Dr Wong said yesterday the man was doing well, although he suffered from nausea and occasional emotional difficulties as side effects of the drugs.

"He's returned back to normal life. He's working. I think he is going to be applying for New Zealand residency."

His work visa had expired and an application for a new one was at first declined by Immigration NZ.

"But on appeal from his lawyer, with medical support", the man had been allowed to stay for compassionate reasons.