Herds of cows are under quarantine in three states, and agriculture officials still lack full accounting of meat that was recalled after discovery of mad cow disease in the United States a month ago.
Cows with links to the Holstein diagnosed with the brain-wasting disease have been found in Washington, Oregon and Idaho. More than 600 animals have been destroyed in the course of the investigation.
The disease has not been detected from tests on roughly 150 of those animals.
“It’s not unusual for an investigation of this type to have multiple states involved,” said Agriculture Department spokeswoman Julie Quick.
Investigators continue to look for about 70 cows that could have come to the United States from the same Alberta, Canada, farm where the sick Holstein was born in 1997. Suspicion focuses on those animals because scientists believe feed containing protein from infected animals is the most likely source of transmission of the disease.
Investigators also cannot rule out transmission from mother to calf.
Mad cow disease, or bovine spongiform encephalopathy, is a threat because humans can develop a similar brain-wasting illness, a variant of Creutzfeldt-Jakob disease, from eating contaminated beef products.
Is the beef supply safe?
Agriculture officials have insisted that the U.S. beef supply is safe, but they nevertheless recommended a recall of more than 10,000 pounds of meat from the sick cow and other animals slaughtered with it on Dec. 9.
USDA officials said the parts most likely to carry infection — brain, spinal cord and lower intestine — were removed before the meat from the infected cow was cut and processed for human consumption.
Most of the meat went to suppliers and stores in Oregon and Washington, while small amounts reached California, Idaho, Montana and Nevada. As of Thursday, USDA officials said they did not know how many pounds of beef had been returned.
Some probably was consumed in the 14 days between the animal’s slaughter and the mad cow diagnosis, they said.
While consumer confidence in U.S.-grown beef has not declined noticeably, foreign markets remain closed to American beef amid a debate about the extent of restriction necessary to protect countries from potentially tainted meat.
The World Organization for Animal Health, which sets international trade standards for animals and animal products, said total bans on beef from the United States and Canada, which also had a mad cow case last year, might go too far.
“An importing country cannot be more trade-restrictive than necessary to achieve the desired national level of protection,” the group said. “Its measures must not be different from those applied to products within the domestic market.”
The decline in beef exports is expected to lead to a $5.5 billion, or 10 percent, decline in net farm income in 2004, according to Global Insight, an economic consulting and forecasting company.
Japan, the largest importer, wants the United States to increase significantly the number of cattle tested for the disease.
U.S. officials have rejected testing at anywhere near the level the Japanese and some U.S. consumer groups want.
Agriculture Secretary Ann Veneman told a congressional committee Wednesday that tests would be run on roughly 40,000 cattle this year, twice last year’s total, and would focus on so-called downed animals that cannot stand or walk unaided as well as cattle that die on the farm.
That number falls well below the recommendations of the animal health organization.
The group said all animals that die on the farm or are terminally ill should be tested. Veneman said there are 400,000 such cattle in the United States each year.
At the same time, however, USDA is preparing to license rapid tests — similar to those in use in Europe and Japan — that could be completed in hours. Mad cow testing currently takes several days at USDA labs in Ames, Iowa.
Among advocates of additional testing are some who believe more tests would yield more cases of mad cow disease. Rep. Earl Blumenauer, D-Ore., among several lawmakers pushing for more aggressive testing, complained that government officials are more interested in protecting the beef industry than consumers.
“Maybe one reason we haven’t found more cases of mad cow disease is because the American public has been eating the evidence,” Blumenauer said.