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The two most recent
and sole native-born cases of bovine spongiform encephalopathy
in the United States may have been spontaneous, or atypical,
strains of the disease, and far different from the more
common form of BSE discovered in Canada and most other BSE-affected
countries.
John Clifford, head veterinarian for USDA, told The Associated
Press over the weekend that while the cases, in Texas and
Alabama, may be very different from typical BSE, it's important
"we treat this as BSE regardless."
Leading prion researchers in Europe have identified similar
atypical cases in cattle in France, Italy and Switzerland.
The disease has affected relatively old animals so far,
as was the case in Texas and Alabama.
The significance of the atypical strain is that it is far
more difficult to detect because the spongy holes in the
brain are not readily apparent. Also, there is evidence
that while typical BSE is spread by infected cattle feed,
the atypical version may not be, and may be spread by some
as yet unknown means. |
