Holstein's Origin Will Be Clue to U.S. Safeguards' Success
By Rob Stein
Washington Post Staff Writer
Tuesday, December 30, 2003; Page A12
The probe into the nation's first mad cow case has reached a crucial juncture in determining whether U.S. cattle are being adequately protected from the dreaded brain disease, experts said yesterday.
In what could be a major advance, investigators announced yesterday that the infected cow was more than six years old, meaning it was born before the United States and Canada implemented the primary protection against the illness -- banning dangerous feeding practices.
And if pending DNA tests confirm the cow came from Canada, as U.S. investigators believe, that could help further reassure Americans and the rest of the world that the case was an isolated incident for the United States and that existing safeguards are effective.
But if the origins and age of the animal remain uncertain, as Canadian officials maintain, the case will continue to raise serious concerns about whether mad cow disease is widespread in the United States, casting a shadow on the U.S. beef industry that would have devastating economic repercussions.
"An important question is to nail down the origin of the cow and try to make a connection with a common origin of disease," said Paul Brown, an expert on mad cow disease at the National Institutes of Health. "The question of whether or not this cow developed the disease from a United States or a foreign source is important to resolve."
And even if the animal was infected in Canada before protective measures were in place, many crucial, difficult questions remain, including exactly how the animal became infected and how many other, similarly infected cows might be carrying the disease.
U.S. agriculture officials also announced yesterday that 81 animals -- eight more than initially thought -- were brought to the United States along with the infected Holstein. Officials are urgently trying to find them to determine whether they, too, may be infected.
"Where are they? Have we eaten them? Are they infected as well?" said Carol Tucker Foreman, a former Agriculture Department official with the Consumer Federation of America. "In all of these questions, there is a level of uncertainty that makes people anxious."
Beyond the specific details of this case, the incident has renewed debate about whether the United States is doing enough to protect animals and humans.
"I think we've had a wake-up call that says we need to look very carefully at the protections in place that keep the risks low," said George M. Gray of the Harvard School of Public Health.
Critics have long charged that steps should be taken to ensure the safety of the food supply, including better policing of the feed ban, prohibiting the slaughter of sick animals and mechanized processing systems, and requiring more animal testing, mandatory recalls of suspect meat and reliable systems for tracking animals.
"I do not believe that this case is a public health crisis," Tucker Foreman said. "But I do think it's a symbol of a problem that we have that needs to be addressed."
No one thinks the Holstein found infected on a Washington state farm poses a significant public health risk. The chances are extremely low that meat from the animal carries the infectious, misshapen protein that causes the disease. The disease does not spread through muscle -- only through ingestion of the brain, spinal cord or a part of the intestine, all of which are removed in the slaughtering process.
And even if infected tissue got into the food supply, the risk someone would get infected is very small. Although thousands of infected cows got into the food supply in Britain, fewer than 150 cases of the human form of the slowly developing disease have been reported. Meat from the infected Washington state animal was recalled primarily to reassure the public.
Of much greater concern is whether the presence of the infected animal indicates that existing safeguards are insufficient for preventing the disease from entering the country and spreading.
After mad cow disease struck Britain, the United States and Canada in 1997 banned feeding cattle ground-up parts of other cattle -- the major way the disease spreads -- and began testing for the disease, known technically as bovine spongiform encephalopathy (BSE).
"If we have indigenous BSE in this country, we have no idea where it's going to turn up next. It makes the future a crap shoot," Brown of the NIH said.
So the fact that the Washington state cow appears to have been born before the ban went into effect, and was not even infected in this country, means this case raises no concerns about the feed ban's effectiveness, experts said.
"It doesn't tell us everything is right, but it's not a direct indication that our feed ban is failing," Harvard's Gray said. "Otherwise it would have meant our feed ban wasn't working and BSE could be circulating."
Concern about the effectiveness of the feed bans arose in May when the first case of BSE in North America was detected in Alberta. If the Washington state cow also came from that Canadian province, that raises the possibility that both cows may have gotten infected the same way -- perhaps through the same batch of infected feed.
"The whole thing would fit together beautifully," Brown said. "That would mean you have a plausible explanation. The number of cattle infected will probably remain very small, and it is a Canadian origin disease and we therefore continue to have no indigenous, homegrown BSE in this country."
But it remains unknown whether the Holstein was born in Alberta or merely passed through the province. While Canadian investigators traced their infected cow to a farm in Saskatchewan, it changed hands a number of times and the source of the infection remains a mystery. The discovery of the infected Holstein in Washington state may help narrow the search for a common cause, if investigators can show that both animals passed through the same hands or got feed from the same source.
In turn, once a source of contaminated feed has been found, officials will have to determine how many other animals ate that feed and locate them. While investigators would like to have an electronic tracking system that follows animals from birth to death, such a system is not available for the tens of millions of animals born, transported and slaughtered in the United States and Canada since 1997. Without such a system, sleuths may have to confront the worst option as the investigation continues to widen inexorably: Wait for another case to narrow the number of choices.
The U.S. feed ban should, however, keep the disease from spreading.
"If we didn't have that in place then you'd have BSE bonfires all over the country," Brown said. "If half the herds in Canada were infected, then you might see some spread. But if it's just a handful of cattle, then I don't think you'd have very much possibility of an epidemic getting started."
Staff writer Shankar Vedantam contributed to this report.
© 2003 The Washington Post Company |
