that foot and mouth disease is some deadly contagion, almost akin to bubonic plague. The truth of course, is that it is endemic in many parts of the world, and they get along reasonably well.
F&M has been in this country since the mid 1800's. It's a viral disease, and one of its cute characteristics is that there are many different strains - it's like Flu in that respect. We worry about it in cattle, but it can affect other cloven-hoofed animals (sheep, pigs and deer), and occasionally (but rarely) humans, too.
The disease is transmitted by animals breathing or ingesting viral particles, which is why the stringent isolation measures are used when there's an outbreak.
F&M kills young animals, and can be pretty horrible for mature ones - their hooves can slough off, leaving them unable to stand. They salivate constantly, and have severe nasal discharges. Pregant animals which are infected will abort their young.
As far as farmers are concerned animals that have been infected with F&M effectively lose their market value. The acute phase (when the symptoms are obvious) lasts about 8-15 days. Afterwards those animals that can recover will do so very gradually. Animals that have recovered from F&M gain weight more slowly and (as a result of secondary infections and mastitis) and produce less milk. There is an overall decrease of 10-25% in productivity for both beef and dairy cattle.
The real problem is that animals which recover remain a danger to healthy ones - they will shed viral particles for up to three years after recovery, and that's why infected animals are slaughtered.