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Scientific findings dismiss maternal transmission but media concern over comtamination in ship holds. (780 Words)

With the foot and mouth outbreak having provided plenty of headline copy for the British press and media over the last 12 months, Bovine Spongiform Encephalopathy (BSE), mad cow disease, and supposedly related variant Creutzfeldt-Jakob Disease (vCJD) have slipped into relative obscurity. What media coverage there has been has related to the continuing intransigence of France to lift its illegal ban on beef imports from Britain, frequent discovery of illegal spinal cord material in beef imported from Europe and a research blunder that might have proved sheep have BSE.

But this week the announcement of research finding that BSE is not transmitted maternally gave the scribes the collective opportunity to indulge themselves. And they did not disappoint, creating fear out of what was really a good news story.

The hard news was that after extensive and varied testing no way was found for the natural transmission of BSE from cow to calf, or indeed was there any evidence that this had ever occurred.

This is itself of limited significance. It will probably bring forward the date at which live cattle, breeding stock, exports will recommence. In terms of the control of the epidemic maternal transmission has not been a major issue in the Britain as it was never viewed as significant. It was not until last September that offspring of diagnosed cows were routinely tested. [Post edit 020228: Offspring of BSE cattle have since 1998 been culled and costs of this programme could be saved. ]

In France which has a whole herd slaughter policy - all cattle on a farm are culled if a single case is detected, however, concern is mounting over the direct and indirect costs of this policy. Evidence that BSE is not transmitted from cow to calf might be used as a pretext to switch to the more logical individual cull policy used throughout the epidemic in Britain.

But the question remained as to how it was that cattle born after the total ban on the feeding of meat and bone meal in August 1996, and there have been five, had contracted the disease. It had been suggested somewhere along the line that, although almost all BSE is contracted from infected meat and bone meal, these exceptional cases might have been the result of maternal transmission.

In response the scientist was reported as saying that his working hypothesis is that it was from cross-contamination of imported vegetable matter feed in ship holds that had previously carried infected meat and bone meal.

Unlikely as this may seem, it is possible. Cross contamination of this nature occurred in British feed mills following the partial, ruminant, ban on feeding meat and bone meal in 1988. Further there have recently been a few unexplained cases of BSE in Japan which imports substantial quantities of feed.

A more likely scenario, however, is that the on-farm disposal of feed containing meat and bone meal in 1996 was not thorough and these cases resulted from this source. The government scientist, of course, could not suggest this, as it would have created even more sensational headlines.

The reality is, however, that the danger to human health in Britain is insignificant. Only animals under 30-months of age enter the food chain and no BSE has been found in these animals. And elsewhere in the European Union all animals over 30-months entering the food chain are tested for BSE.

The BSE situation in Britain is, in truth, winding down much as anticipated. New cases of BSE from the naturally declining number of cattle born before the meal and bone meal ban in 1996, are now down to a rate of about one a day and Britain has now slipped below France and Ireland in the BSE league tables.

The incident of vCJD, the rare but fatal human disease which is commonly associated with BSE is increasing but not at the explosive rate predicted by some. In 2001 20 cases were diagnosed, 30 percent lower than 2000, but the second largest annual figure since the disease was recognized in 1994.

The public, however, may not be assured by all this. What can be done about holds of ocean vessels that may have carried contaminated meat and bone meal five years ago is difficult to imagine. BSE is known to be a very resistant organisms surviving temperatures that would be impossible to apply to ocean vessel holds and conventional freight hygiene procedures such as fumigation and steam cleaning are not likely to fit the bill.

The Food Standards Agency which is normally fast off the mark to assure or warn the public in such situations has so far been strangely silent.

Their hope, no doubt, is that the public, if not the media, will recognize this is a nonevent. And that is progress.

February 27, 2002