Bovine Spongiform Encephalopathy (BSE or Mad Cow Disease) is a neurodegenerative disease which gradually destroys cattle brains by turning them spongy. It was first officially documented in 1986 with approximately 180,000 cows dying from it in Britain and millions more slaughtered to eradicate it from suspect herds.

Early theories suspected the disease originated from a single cow which developed the disease spontaneously through a unique, random mutation of a protein in the brain and nerve cells. When other cattle ate the ground-up remains of this cow they also developed the disease. The disease spread as more and more cows ate the infected feed. Alternatively the disease was thought to have come from the sheep equivalent of BSE and spread the through the cows feed.

Another theory is that the epidemic was started by a single diseased African antelope which was imported into the country by a safari park. When it died the antelope was converted to feed for cattle and the process of infection began.

Mapping the spread of BSE in the United Kingdom:

Scientists at Massey University in New Zealand have mapped the spread of BSE by plotting the number of BSE cases per 100 cattle per square kilometre. This makes it easier to identify areas of disease excess.

The scientists used agricultural census data at the farm level to map cases of BSE against farm type (beef or dairy) and the total number of cattle on each farm.

Snapshots in time of the extent of the disease on each of the farms shows how the epidemic developed. As time progressed a trend showed the disease density higher in the southwest region of England and in the southwest of Wales.

Spatial modeling techniques were used to test the various theories of how the disease spread and the theory of a single origin in the southwest of England in 1971 fits the spread of the disease both spatially and temporally.

Back then antelope were introduced into Britain to populate safari parks which had opened. Most of those parks were in the southwest of England. Many species of antelope are susceptible to a similar disease and substantial numbers died of the disease in wildlife parks.

For more information on BSE try the New Scientist Web Site.