February 10, 2004, Pg. A01

U.S. Ends Investigation of Mad Cow Case; Officials Fail to Find Two-Thirds of Animals at Risk of Infection

By Shankar Vedantam

Federal officials ended their investigation into the country's first case of mad cow disease yesterday after failing to locate almost two-thirds of the 80 cattle that had entered the United States from Canada with an infected Holstein.

The 52 missing animals include 11 cows believed to be at higher risk because they were born about the same time as the Holstein and may have eaten the same contaminated feed. "The paper trail has gotten cold; we have not been able to trace those animals," said W. Ron DeHaven, chief veterinary officer at the Department of Agriculture. "Some of them very likely have gone to slaughter," he said.

Although DeHaven said the seven-week investigation had been exceptionally successful -- "We never expected to be able to find all of them; it's remarkable we found as many as we did" -- the deputy USDA administrator had tried to soothe public fears in December by promising that most of the herd would be found alive.

"Most of them are likely still alive," he said Dec. 27, according to a USDA transcript. "Because the records that are kept on dairy cattle are typically very good . . . we feel confident that we are going to be able to determine the whereabouts of most, if not all, of these animals within the next several days."

Yesterday, DeHaven said that many of the animals' ear tags had been lost and that the chances of finding the rest of the herd was "pretty slim at this point."

"It's time to move on," he said.

Department officials said the end of the investigation could help prompt other countries to resume imports of U.S. beef. But the announcement left open the questions of where the missing cattle were, whether other animals had been infected and how likely it was that humans had eaten meat from infected animals.

Officials said their decision to halt the investigation was supported by an international panel of experts. And they insisted that even if other animals had mad cow disease, the risks to humans were low.

A 1997 feed ban diverts potentially infectious tissues from both the human food supply and the animal feed supply. Although those measures were believed to be adequate until the infected Holstein was discovered on Dec. 23, additional tissues have since been deemed potentially infectious and are being diverted, and greater numbers of animals are now considered at risk.

Since then, beef sales within the United States have remained stable, but dozens of nations have banned imports of U.S. beef, crippling the country's $3.6 billion beef export industry. Yesterday, DeHaven said officials are working to reopen trade with two of the biggest importers, Japan and Mexico.

"The investigation is not completed; it just failed," Tadashi Sato, agricultural attache at the Japanese Embassy, said about whether the end of the investigation would prompt his country to lift its ban. "It failed because it could not identify all the cattle."

Separately, DeHaven said that several nations have restricted imports of U.S. poultry after the discovery of avian influenza last week in Kent County, Del. That virus is genetically different from one devastating the poultry industry in Southeast Asia, he said, but South Korea, Singapore, Poland and Japan have restricted U.S. imports, and Hong Kong is considering such action, he said.

The search for the cows began immediately after federal officials announced that a Washington state Holstein slaughtered Dec. 9 at a Moses Lake facility had tested positive for mad cow disease, or bovine spongiform encephalopathy. The Holstein and its herdmates had come from an Alberta farm in 2001.

Because mad cow disease is transmitted through infected feed, and because a second Canadian animal had been found infected in Alberta in May, investigators feared that other animals in the herd had eaten contaminated feed. Only a small fraction of cattle exposed to bad feed become sick, but quantifying the exact risk to an individual animal is difficult.

Officials investigated 189 premises and examined more than 75,000 animals, DeHaven said. The effort produced 255 "animals of interest" from 10 facilities in Washington, Idaho and Oregon, including 28 animals from the original herd. Those included 14 animals that were born about the same time as the infected Holstein. Young animals are especially vulnerable to contaminated feed.

The 255 animals were killed. None tested positive for mad cow disease, DeHaven said. While some of the missing 52 animals, including 11 from the birth cohort, could have been among those killed, officials could not prove or disprove it.

"We think they represent very little risk," DeHaven said of the missing animals, adding that "even if there are more positive animals out there," the 1997 safety bans would ensure that infected tissue was kept out of the food supply.

Federal officials recently launched a program to track cattle from their birth farms to slaughterhouses.

Stephen Sundlof of the Food and Drug Administration said yesterday that agency officials had seized 2,000 tons of meat and bone meal that had passed through two processing facilities along with meat from the infected Holstein. The material was diverted from human consumption and animal feed and will be safely disposed of, he said.

Staff writer Marc Kaufman contributed to this report.

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