BSE is an interesting disease from a medical standpoint because of the causative agent, prions (pronounced pree-ons). A prion is an infectious protein that is similar to a virus, but not a typical virus. Unlike viruses, prions aren't alive, so they can't be killed with the usual disinfectants. The body does not mount a typical viral immune attack against prions, either. Prion proteins can be denatured, but only at extremely high temperatures or with very strong chemicals, either way, not consistent with animal life so these are not treatment options. Diseases caused by prions are referred to as TSEs -- Transmissible Spongiform Encephalopathies.
How do prions infect cows?
The most common mode of infection is via feeding cows contaminated feed -- feed that contains animal proteins (from sheep or cows). Researchers are still studying modes of transmission and if heredity/genetics plays a role in an individual animals susceptibility to, or protection from, acquiring this disease.
How is BSE diagnosed?
BSE is suspected in animals that exhibit neurological problems such as: staggering, general loss of motor control, dementia/behavioral changes, increased startle reflex, weakness, weight loss, and decreased milk production. BSE is diagnosed by examining the brain tissue of the deceased animal and finding characteristic "moth eaten" appearance of the brain tissue.
How long does it take for BSE to develop in cattle?
BSE has a long incubation period, meaning that it can take months or years to show clinical signs. Once a cow starts showing signs, it is often terminal within 3 months.*
* (Merck Manual, 8th ed.)
Can humans catch Mad Cow disease?
Technically, no, since this is a bovine disease. However, there is a human version, and it is called Creutzfeld-Jacob Disease, that has been linked to eating infected cow meat. This is an area of intense research at the present time, searching for clues about diagnosis, transmission and risk factors.
