Doctor rules out brain snip for CJD

By MARTIN JOHNSTON, AINSLEY THOMSON and HELEN TUNNAH

The doctor caring for the man who may have New Zealand's first case of variant Creutzfeldt-Jakob disease has ruled out doing a brain-tissue biopsy, the only definitive test available.

This is despite a leading neurologist, Associate Professor Martin Pollock, saying a biopsy would be justified to confirm the disease and help track its cause.

It would involve drilling through the skull to remove a small piece of tissue.

Variant CJD, an invariably fatal brain-wasting disease, is thought to be caused by eating meat or meat products from cattle infected with mad-cow disease (bovine spongiform encephalopathy, or BSE).

Test results are awaited on the 26-year-old farm worker to see if he has vCJD. Alzheimer's or other brain diseases are possibilities. He is in a stable condition in a general ward at Waikato Hospital in Hamilton.

Professor Pollock, head of the Otago University-based CJD registry, said that if these weaker tests were equivocal, or even positive, it would be important to make a certain diagnosis by biopsy.

"It's such a pivotal case [and would be] the first one in Australasia. Getting tissue from the brain under the microscope, we would be really sure about that diagnosis."

But Dr Paul Timmings, the man's neurologist, disagrees, saying "a brain biopsy cannot be justified, given we can offer no specific treatment".

A Ministry of Health spokeswoman said a brain biopsy would be unethical.

Professor Pollock said neurosurgeons were usually unwilling to perform brain biopsies on possible vCJD cases because of the risk of contaminating the operating theatre and the difficulty of killing the disease's infective agents, called prions.

"If done by a competent surgeon there should be very little danger to the patient.

"It's mainly the difficulty of how you handle the drills, which are very expensive, and the instruments, and incinerating them is an expensive exercise.

"The instruments are usually put in a particular furnace that heats to a very high temperature and destroys them."

Two bodily samples from the man - spinal fluid and a tonsil - have been sent to Australia for testing in addition to other tests. Results of the fluid are expected on Monday and the tonsil within a fortnight. The fluid test is at best suggestive and the tonsil test has high rates of false positives and false negatives.

Dr Timmings said the false negative rate was 25 to 30 per cent. "It is possible the diagnosis might simply change from possible to probable."

Once all the tests had been completed, the man might be able to go home.

The Waikato District Health Board said family and staff looking after the man were not at risk of infection as there was no evidence vCJD was transmitted by saliva, bodily secretions or excreta.

Board chief executive Jan White said the family were being "strongly supported".

The ministry revealed the man's illness on Thursday. It had wanted to wait for the test results, but said it had to dispel mistaken reports from Britain of a foot and mouth disease outbreak here.

More than 130 people have contracted vCJD, almost all in Britain, where the median age of patients at death is 28. It often starts with depression and progressively affects movement and memory. Patients generally survive for just over a year from diagnosis. It is thought likely that if the man does have the disease, he would have contracted it years ago from imported food.

Imports of potentially risky beef or beef products from Britain were banned in 1996.

Agriculture Minister Jim Sutton yesterday repeated assurances that NZ cattle does not have BSE. "For 50 years we have not allowed imported meat-and-bone meal."