WASHINGTON, Dec. 24 (UPI) -- International barriers to beef from the United States increased Wednesday after the first suspected case of mad cow disease was found.

Japan, South Korea, Singapore, Malaysia, Taiwan, Thailand and Australia were the first to ban imports of beef, joined soon after by Russia, South Africa, Ukraine, Mexico and Israel.

A single, Holstein cow tested positive for mad cow disease on a farm near Yakima, Wash.

USDA secretary Ann Veneman said Tuesday it was too early to call the test results an isolated incident, although she stressed there is no indication of a larger problem with the U.S. beef supply.

Shares in hamburger giant McDonald's Corp.fell by about 5 percent on the New York stock exchange, although the company said its supply chain was not linked to the suspected "mad cow" disease case.

Washington Gov. Gary Locke said in a statement the results were "presumptive," and that scientific confirmation of the presence of bovine spongiform encephalopathy was due in three to five days from a testing center in England.