February 8, 2004 Sacramento Bee by Jon Ortiz

That's the one thing that U.S. agriculture officials, foreign governments and consumer groups can agree on.

Looking at how the United States tests for mad cow disease illuminates why estimates on the number of other infected cows range from zero to the thousands. And it also shows why opinions vary on how best to test for bovine spongiform encephalopathy, or mad cow disease.

The U.S. Department of Agriculture will not guess the number of undetected mad cows, saying its testing is not a scientific sampling that allows extrapolation, nor is it designed to keep the food supply safe.

"We cannot give you a specific count (of potentially diseased animals) because that's not what our surveillance program is designed to do," said Jim Rodgers, spokesman for the USDA's Animal and Plant Health Inspection Service, which oversees mad cow testing.

"The program isn't designed to find every case of disease," he said. "It's not designed so that a rancher can say, 'I raise only 100 percent (mad cow)-free beef.' "

Although the inspection service tested the brains of 20,000 of the 35 million cows slaughtered in the United States last year, most of those were so-called "downers" too sick to walk. Those were targeted because scientists think such animals are at highest risk for mad cow. Cows in the throes of the disease often can't walk, and downer cows usually are older than 30 months - the generally accepted incubation time for mad cow.

Of the cattle slaughtered in the United States last year, approximately 200,000 were downers.

By narrowing its focus to high-risk animals, the USDA says that its mad cow surveillance can catch one mad cow in a cattle population of 1 million. By that notion, 35 of the 35 million cows slaughtered in the U.S. last year could have been infected and their meat sold in stores and restaurants like the infected cow found in Mabton, Wash.

But the USDA's narrow sampling pool makes that math impossible. Its program does not use scientific sampling by which a random sample statistically represents a larger population.

The USDA, which plans to test 38,000 cows this year, estimates it would need to test 3 million cows chosen by scientific sampling to accurately reflect the overall health of the 100 million cows in the U.S. herd.

But the department stands by its mad cow program, saying it tests cows most likely to be sick. "Our program is supposed to determine if there is a disease in a population of animals, that's it," Rodgers said.

The USDA banned "downer" cows from the food supply on Dec. 30. It has not set new standards for how many downer cows and how many apparently healthy cows will be tested.

Praise for the testing program has come from the very top of the USDA, with Agriculture Department Secretary Ann Veneman characterizing it as "aggressive."

Consumer groups, however, have criticized the process for years.

"This is an agency that has created and maintained an unscientific test program that doesn't address public health issues," said Felicia Nestor of the Government Accountability Project.

Harvard risk analyst Joshua Cohen said that the number of BSE-infected cattle in the national herd could range between "zero and a few thousand." The reason for the wide swing, he said, is that the USDA targeted downer cows, skewing the math.

"Those factors taken together mean that (the Washington cow) could be an unusual case," Cohen said. "This wasn't a random sample. It was a sample targeted at a particular kind of cow. That means you can't project with any certainty how many other cows in the general population are sick."

Cohen co-authored a 2001 study on mad cow disease by Harvard's Center for Risk Analysis. The USDA often cites the study as proof their system is adequate.

"I believe we're in the lower end of that range, but I wouldn't bet my life that no more cases exist," Cohen said. "You can never say never."

He thinks that limited testing is acceptable, given its cost and relatively low risk of human illness - as long as testing targets high-risk cows.

"When you're looking for a needle in a haystack, you've got to look through a lot of hay," he said. "Unless the needle has shaken down to the bottom so you can narrow down where to look for it."

USDA critics say the current system is full of holes that put public health at risk.

In California, about 2,200 of the state's 1 million slaughtered cattle were tested for mad cow each of the last two years, according to the state Department of Food and Agriculture.

Between 1997 and 2003, California's dairies and ranches submitted a total of 5,217 cows for testing, according to state records. State testing statistics for previous years were not available by The Bee's deadline.

In the 12 years from 1990 to 2001, 16,829 cattle in the United States were tested for mad cow. Then the Harvard study called for more testing, and the USDA upped the number to 19,990 in 2002 and 20,543 last year.

"This country isn't serious about finding the disease now, and we were positively sleepwalking a few years ago," said Ira Krull, a mad cow expert at Northeastern University and outspoken critic of the USDA.

Nestor and other consumer advocates, including Consumers Union and the Consumer Federation of America, want the USDA to adopt the United Kingdom's mad cow policy. The UK tests every cow older than 30 months - a program that caught 425 cases there last year.

Adopting the same policy here would mean testing more than 6.3 million cow brains annually, or about 17,000 brains per day at a cost of about $50 each.

The beef industry hates the idea of casting the mad cow net wider, saying more tests are needless and costly and that fears about infected cows in the food chain are unfounded.

"It would be like a physician testing every patient who walked in the door - male, female, young or old - for prostate cancer," said Ben Higgins, spokesman for the California Cattlemen's Association, which supported the USDA's ban on downer cows from human consumption. "We feel that the current safeguards against the introduction and spread of BSE in the U.S. are highly effective."

The government and the beef industry point to estimates by the Centers for Disease Control and Prevention. Those place the odds of a human eating mad cow-tainted beef in any single meal at 1 in 10 billion - roughly 14 times less likely than being struck by lightning.

Broadening testing is not without risks. The harder the USDA looks for the disease, the more likely it is to find it, said Harvard's Cohen.

Such revelations could sap the confidence of U.S. consumers, who've kept eating beef despite the December discovery of the single mad cow. More BSE cases probably also would extend the embargoes slapped on U.S. beef by more than 40 countries.

Yet reopening the $3.8 billion overseas market depends on convincing those countries that the USDA is doing everything it can to find mad cow disease. South Korea, for example, has twice spurned trade envoys, including USDA Undersecretary J.B. Penn, by saying it would not resume beef imports until the meat is "scientifically proven safe."

That could mean a policy such as the one in Japan, where all slaughtered cattle have been tested since mad cow surfaced in 2001. Testing there has found nine cases so far.

"How you shape a testing policy depends on what you view the purpose of the surveillance is," said the USDA's Rodgers. "Is it to find an animal disease in a population? Do you go at it from a food safety standpoint, or a marketing standpoint? If it's marketing, then you do what some other countries are doing."

But mad cow surveillance in this country also is a marketing ploy, said Nestor of the Government Accountability Project. She asserts that the USDA has been slow to expand testing because of what she says are its contradictory mandates to both regulate the beef industry and to promote beef sales at home and abroad.

"The government talks about how catching this one case proves that the system works, but the fact is that it's really, really broken," she said. "It's like having a shredded fishing net and you just happen to catch one fish. How many did you miss?"

The question concerns Dr. Stanley Prusiner, a University of California, San Francisco, physician who won a Nobel Prize in 1997 for his discovery of prions that cause mad cow disease.

He theorized that BSE is triggered by prions that lodge in the intestines, brain and spinal cord. Humans who eat contaminated beef products can develop variant Creuzfeldt-Jakob disease, a fatal malady that slowly eats holes in the brain.

Prusiner predicted eight years ago that mad cow disease was already present at low levels in the United States and faulted the government for not testing more rigorously. Last month, he again urged officials to broaden the scope of testing.

"I cannot understand, as the father of two daughters, why our country remains unwilling to adopt the Japanese policy of testing every cow and bull destined for consumption by humans," Prusiner told the Congressional Food Safety Caucus in Washington, D.C. "The problem of prion contamination of the food supply will not go away."