New cases of BSE infected cows in Japan and Canada.

Tuesday, January 24, 2006
Meatingplace.com

Officials on both sides of the U.S.-Canadian border are saying that the discovery of BSE in a 6-year-old Alberta animal "is not unexpected," but rather consistent with projections that additional Canadian cases would be uncovered as a result of "residual infectivity" following the ruminant-to-ruminant feed ban Canada implemented in 1997.

Feed residue may be culprit

Evans explained that because even small amounts of infective tissue — even as small as a grain of sand — can transmit BSE when animals are at their most susceptible age, it's not unreasonable to assume that animals can contract the disease from residue remaining on a feed bin or feed auger. He also said "the potential [for infection] will always be there" as long as other potential vectors of infectivity, including poultry litter in cattle feed, exist. "That's why we continue to perform surveillance," he said.

Hodges said ongoing surveillance in Canada and the United States indicates "a high level of statistical confidence that if BSE exists in either country, it exists at very, very low levels."

The geographic location and age of the animal identified Monday are consistent with the three domestic cases previously detected through Canada's surveillance program. Evans said the fact that the age of the infected animal, born in April 2000, is consistent with the bottom threshold of the other three infected animals discovered — 70 months to 80 months — is reason for optimism. He cited the Harvard Risk Assessment for BSE, which indicates that once BSE is significantly reduced in cattle populations, the disease eventually dies out. "That said, I wouldn't want to identify a date threshold, because it would be based upon assumptions that may or may not happen," said Evans.

Evans said that when Canada uncovers a case of BSE, a molecular assessment of the diseased tissue is performed to determine whether the case has a common affiliation with other cases. He also indicated that a live animal test for the disease, if it becomes available, would help in further eradicating the disease.

Japan logs 22nd case of BSE

A 5-year-old cow that died last week on a farm on Hokkaido Island on the north end of Japan had bovine spongiform encephalopathy — the 22nd case in Japan, according to Japan Economic Newswire.

The cow was born in September 2000, before Japan's 2001 implementation of a ban on meat-and-bone meal in cattle feed.

The Hokkaido prefectural government will investigate the route of the BSE infection analyzing feeds, Japan's Agiculture Ministry indicated. The cow tested positive in a series of screenings at a meat inspection institution in Hokkaido, it said.