Last week, as reports of the first case of US mad cow disease in 6 years circulated, researchers discovered that the prion responsible was a rare L-type version, also called an atypical variant, rather than the more common C-type, associated with human transmission of the disease in the United Kingdom. Although there is evidence in primates and mouse models that the L-type is more contagious, it’s not clear whether the same would be true in humans, reported Nature.
Researchers are also looking into how the cow came down with the disease in the first place. “Long term studies are beginning to look at whether or not it’s capable of transmission orally through feed, but we don’t have the data yet,” Linda Detwiler at Mississippi State University’s College of Veterinary Medicine told Nature. If it is transmissible through feed, like the C-type, , other cows could be infected. Alternately, the disease could have started from a gene mutation in the affected cow. But, said Detwiler, “no one knows the origin at this point.”