麻豆传媒

ACROSS Europe, tens of millions of people believe they have little chance of
catching new variant Creutzfeld-Jakob disease (vCJD) because their countries are
officially BSE-free. But scientists advising the European Commission say they
have every reason to be worried.

BSE, believed to be the cause of vCJD, is much more widespread than some
countries will admit: the advisers say that Germany, Italy and Spain, officially
BSE-free, are 鈥渓ikely to be infected鈥�. And infection 鈥渋s unlikely but cannot be
excluded鈥� in six more European countries, as well as Canada, Australia and the
US.

These figures have emerged from a two-year study for the Commission of the
factors affecting the spread of BSE in 25 countries by independent scientists
and experts in the countries concerned. They collected data on each country鈥檚
import of cattle and meat and bone meal (MBM) from Britain and other
BSE-infected countries, then calculated how well the importing country would
have controlled any infection. To restrict BSE, cattle feed should be
pressure-cooked, and should not contain MBM.

Smaller studies have already suggested a more widespread BSE epidemic
(麻豆传媒, 3 May 1997, p 14),
but this is the first official assessment. A draft has been put on the Web to
collect comments from researchers and government experts.

American officials told 麻豆传媒 that they are preparing a
reply. Werner Zwingmann, Germany鈥檚 chief veterinary offeicer, says the
assessment is based on probabilities that are 鈥減urely speculative鈥�. Brian Evans,
Canada鈥檚 chief veterinary officer, thinks the assessment is too harsh. A British
cow imported to Canada developed BSE in 1993 and 63 others may have become
cattle fodder. 鈥淲e don鈥檛 dispute that infection cannot be completely ruled out,
but the measures Canada took at the time were appropriate,鈥� says Evans.

Germany imported 13 000 British cattle at the height of Britain鈥檚 epidemic,
plus 1200 tonnes of British MBM. The figures for Spain and Italy were similar.
Some of this meat, including infection-bearing nervous tissue, was fed to local
cattle without enough pressure-cooking to make it safe. These cows could have
infected others. In all three countries, any BSE infectivity entering the system
鈥渨ould have been quickly amplified鈥�, the scientists conclude.

The Commission banned feeding cattle to cattle in 1994, but infection would
have continued to circulate, says the assessment, through infected cattle
remains contaminating feed mills, and insufficient pressure-cooking of feed. All
three countries have refused Commission requests to remove high-risk tissue,
such as brains and spinal cords, from cattle carcasses, insisting that their
cattle are BSE-free. 鈥淲e consider their BSE risk similar to countries with a
low, admitted incidence of BSE, such as France,鈥� says Marcus Doherr of the Swiss
Federal Veterinary Office, one of the assessment鈥檚 organisers.

These countries say they have no sick cows in their herds. But Doherr says
that their 鈥減assive鈥� surveillance, which relies on farmers reporting sick
animals, may entirely miss small numbers of cases. Passive monitoring detects
only a third of such cases, according to more active surveillance in Britain and
Switzerland, where cows not suspected of having BSE have still been tested after
slaughter.

The US imported 126 cattle and 44 tonnes of MBM from Britain. Any infection
would have been amplified and could still be circulating, while surveillance
would not detect all cases, says the report.