Hong Kong, Australia, Taiwan, Singapore, Thailand, Malaysia and Russia followed suit soon afterwards.
Japan's Agriculture Ministry said the country is indefinitely banning beef imports, depriving American exporters of their largest overseas market.
In Seoul, South Korea, the government halted customs inspection of U.S. beef, a move that effectively keeps U.S. beef from reaching its domestic market.
The suspensions came only a few hours after the U.S. government announced that a Holstein cow on a Washington state farm tested positive for mad cow disease, marking the disease's first suspected appearance in the United States.
The Bush administration on Tuesday tried to reassure Americans their food is safe.
A Japanese ministry official, speaking on condition of anonymity, said the ban applied to beef and beef products and took effect immediately.
Japan is the largest overseas market for U.S. beef. Exports totaled $842 million in 2002, according to the U.S. Meat Export Federation.
Japanese authorities have been especially leery about mad cow disease since the nation's herds suffered the first recorded outbreak of the disease in Asia in September 2001, causing meat consumption to plunge. Consumption, however, has since rebounded.
Tokyo moved ahead with the ban despite assurances from U.S. officials that the American beef supply was safe.
The Washington state cow marks the first suspected appearance of the brain-wasting disease in the United States, the Bush administration announced Tuesday.
Washington State University agricultural economist Thomas Wahl told CBS News Correspondent Stephan Kaufman the U.S. food supply is safe, but he admitted that public perception following the first suspected U.S. case of mad cow disease may hurt the beef industry.
Wahl said he never expected a case of mad cow disease to surface in the United States, and the news of the case of mad cow comes at a time when the beef industry was enjoying renewed consumer interest.
Wahl told Kaufman, when he asked his mother-in-law if she'll continue to eat beef, she said, "Well, I'll eat what's in my freezer," and said her response may be a good barometer of what's in store for cattle farmers.
Agriculture Secretary Ann Veneman said the slaughtered cow was screened earlier this month and any diseased parts were removed before they could enter the food supply and infect humans. Fear of the disease has brought economic ruin on beef industries in Europe and Canada.
"We remain confident in the safety of our food supply," Veneman told a hastily convened news conference. The farm near Yakima, Wash., where the cow originated, has been quarantined as officials trace how the animal contracted the disease and where its meat went.
"Even though the risk to human health is minimal, we will take all appropriate actions out of an abundance of caution," she said.
The beef industry also rushed to assure consumers.
"Our government is on top of it. Our industry is on top of it and the American public can feel safe eating beef," Chandler Keyes of the National Cattlemen's Beef Association told CBS News Correspondent Wyatt Andrews.
Mad cow disease, known also as bovine spongiform encephalopathy, eats holes in the brains of cattle. It sprang up in Britain in 1986 and spread through countries in Europe and Asia, prompting massive destruction of herds and decimating the European beef industry.
A form of mad cow disease can be contracted by humans if they eat infected beef or nerve tissue, and possibly through blood transfusions. The human form of mad cow disease so far has killed 143 people in Britain and 10 elsewhere, none in the United States. Blood donors possibly at risk for the disease are banned from giving.
Wary of the potential economic impact on their American market, beef producers quickly sought Tuesday to reassure consumers that infected meat wouldn't reach their tables. "There is no risk to consumers based upon the product that came from this animal," said Terry Stokes, chief executive of the National Cattlemen's Beef Association.
Veneman also assured Americans the screening system worked, and no foul play is suspected. "This incident is not terrorist-related," she said. "I cannot stress this point strongly enough."
President Bush was briefed a few times on the development Tuesday and was confident Veneman's department handling the matter properly, the White House said.
Veneman said the Holstein, which could not move on its own, was found at a farm in Mabton, Wash., about 40 miles southeast of Yakima, and tested preliminarily positive for the brain-wasting illness on Dec. 9. Parts of the cow that would be infected — the brain, the spinal cord and the lower part of the small intestine — were removed before the animal went to a meat processing plant.
Samples from the cow have been sent to Britain for confirmation of the preliminary mad cow finding, Veneman said. The results will be known in three to five days. Veneman said consumers can get daily updates by reading the department's Web site or by calling 1-866-4USDACOM.
She said tests are made of all downed cows — old cows that are not mobile — that are sent to slaughterhouses.
Veneman said the Agriculture Department has had safeguards in place since 1990 to check for mad cow disease and 20,526 cows had been tested in 2003 in the United States.
"This is a clear indication that our surveillance and detection program is working," Veneman said.
U.S. beef remains "absolutely safe to eat," she said.
The government is depending on a mix of quarantine and detective work to figure out how mad cow disease apparently infected the cow in Washington state.
The nation's mad cow emergency plan — never before used — is to cordon off any cattle that could have come into contact with the infection.
Keeping any possibly infected cow out of the food chain is crucial, as a human version of the disease that literally eats holes in the brain is believed spread by eating meat tainted with infected brain or nerve tissue. The human illness, with the unwieldy name new variant Creutzfeldt-Jacob disease, has claimed 143 victims in Britain and 10 elsewhere, but none so far in the United States.
Already, the farm near Yakima, Wash., has been quarantined as the government awaits the last of three tests on the suspect cow's tissue to confirm the presence of BSE, bovine spongiform encephalopathy. That final test is performed in Britain, where BSE first erupted in cattle in 1986.
Once confirmed, all the animals in that herd probably will slaughtered so their brains, too, can be tested, said Food and Drug Administration Deputy Commissioner Lester Crawford, a veterinarian who oversees the agency's BSE work.
Key is tracing the source of the first infection to see how the U.S. firewall against this disease was breached.
Beef and cattle imported from countries known to have BSE has long been banned.
But the nation's main defense is a 1997 ban on giving cattle feed made from the protein or bone meal of sheep or other mammals — because that feed is thought to be the way mad cow disease originally spread.
So the first question is whether the cow was illegally imported or ate feed that illegally contained BSE-bearing protein.
Another possibility depends on the cow's age, which wasn't immediately known. If the cow was more than 6 years old, she could have received tainted feed before the FDA's ban began, Crawford noted. The disease's incubation period can be as long as eight years.
A second part of the probe is to trace every cow the ill one — and any others found to be ill — came into contact with, so they also can be quarantined and tested to see if the infection spread.
Canada has had two cases of BSE-infected cows, once in 1993 and once last spring, but never was able to pinpoint the source of infection, Crawford noted. "We would hope to be able to nail it down," he said.
Scientists have long warned it was only a matter of time before BSE reached U.S. cattle, because safeguards can't be foolproof.
Still, "we have in place a system in this country to dramatically reduce the risk of any infected bovine getting into the food system and being consumed," said Michael Osterholm of the University of Minnesota, who has advised the federal government on food-safety issues.
"One case does not make for a crisis," he stressed.
Extra layers of protection are in place at the slaughterhouses, where inspectors are supposed to prevent sick animals from being killed for human consumption.
In addition, the Agriculture Department had the brains of more than 20,000 cows tested for signs of BSE in the last year, triple the number from previous years.
According to the National Cattlemen's Association, any non-ambulatory cow, such as the one in Washington state - as well any cow with signs of neurological disease and all cows over 30 months old, because BSE is more common in old cows — are tested.
Critics say there are loopholes. Europe tests far more cattle for BSE, for example. Also, BSE is caused by rogue proteins called prions that collect in the cow's brain, spinal cord and other nervous system tissue. Processors are supposed to remove the spinal cord to minimize health risks, although a 2002 report found not all processors completely follow that rule. The Agriculture Department last spring began more careful testing to ensure compliance.
"Virtually every aspect of our BSE prevention program will be reevaluated," said FDA's Crawford.