NZ lamb sector downplays 'theoretical' risk of BSE in sheep

New Zealand and Australian meat industry executives are scrambling to discount the latest British scare over mad cow disease - that 100,000 people could die if mad cow disease has infected Britain's 40 million-head sheep flock.

British scientists have an urgent mass screening programme to detect infection levels, even though there is no proof the brain-wasting disease has spread to sheep.

The "worst, worst, worst-case scenario" study shows there may be a greater risk of contracting the human form of mad cow disease from eating sheep rather than beef, if it were present in sheep.

A human form of mad cow disease, variant creutzfeldt-jakob disease (vCJD), is thought to be contracted by eating beef infected with BSE.

But Meat New Zealand's general manager of trade policy, Gerry Thompson, said today the latest warning would have only a "minimal impact" on New Zealand lamb.

New Zealand and Australia are recognised in Europe as free from bovine spongiform encephalopathy (BSE).

"It's important to note that the UK's own Food Standard Agency is reported as saying the risk of BSE in sheep remains theoretical and they are not advising UK consumers against the consumption of lamb," Mr Thompson said.

Commenting on whether the UK warning might affect New Zealand lamb exports, he said: "We would not expect a significant impact on sheepmeat consumption unless BSE were actually found in European sheep.

"Even in that event we would expect the impact on New Zealand lamb to be much less severe than on European lamb because of our disease-free status."

New Zealand exported around 90,000 tonnes of lamb and mutton to Britain in the year to September 30, 2001, with a value of $520 million. Meanwhile New Zealand was ensuring that UK trade and consumer groups continued to be aware of the safety and quality of New Zealand lamb.

"In that sense it is 'business as usual'," Mr Thompson said.

New Zealand has never had a case of BSE, has regulations against feeding ruminant protein - such as sheep or cattle meat or bone meal - to other sheep and cattle. It does allow blood and bone to be spread as a fertiliser on pastures where sheep and cattle graze.

In Australia, where meat industry executives have taken a similar stance to re-assure farmers, Professor David Adams, a senior scientist with Agriculture, Fisheries and Forestry Australia, said "it is really the worst, worst, worst-case scenario that this paper is looking at".

"This whole BSE thing is becoming a bit crazy because the real risks are being managed," he said.

"We have this biochemically complex disease with an astonishingly simple control measure: don't feed (cattle and sheep) meat and bone meal."

BSE is not found in Australia. The feeding of meat and bone meal to ruminants, such as cattle and sheep, is banned in this country.

Prof Adams said that British sheep were fed on meat and bone meal, so there were grounds to theorise that BSE could have entered sheep in the UK. There is a theoretical risk that BSE infection could be masked by scrapie -- a similar type of disease in sheep believed to pose no risk to human health.

Prof Adams said assays on the brains of more than 400 British sheep infected with scrapie found no evidence of BSE. But statistically, it was possible 1.7 per cent of the scrapie cases had BSE present. Based on this assumption, the British epidemiologists has said that in theory human BSE cases from sheep could reach 150,000, compared with a maximum of 50,000 from beef.

"That is the worst-case scenario, it takes no account of the fact that specified risk materials like brain and spinal cord are taken out of sheep in the UK as a precaution now," Prof Adams said.

The study, published in Nature, assumed BSE in sheep would act in the same way as scrapie, but BSE in deliberately infected sheep was very different from scrapie, which has an infection period of up to six months. BSE sheep died within two days.

The British scientists said they were not trying to evaluate the probability that BSE has entered the sheep flock, but had taken the pessimistic assumption that infection had already occurred to explore its potential extent and pattern of spread.

- NZPA