Foot-and-mouth disease, which afflicts cloven-hoofed animals like sheep, cows and pigs, is extremely easy to spread. Although humans almost never catch the disease, they can carry it on boots and clothing. The virus can also be airborne, transmitted from one animal to another, or contracted through contaminated feed. Out in the countryside, leaping flames lit the night sky over snowy fields as workers built giant bonfires of livestock carcasses. Wholesale slaughter is considered the only way to stop the epidemic, and so great is the fear of contagion that the animals' bodies are burned to ash and then buried in deep pits. Exhausted veterinarians were working around the clock testing livestock, and distraught farmers examined their herds for the dreaded telltale blisters on the animals' feet and mouth. The ripple effects of Britain's week-old outbreak of foot-and-mouth disease spread far beyond the farm Monday, as all sorts of everyday activities were curtailed in the struggle to stem the virulent livestock ailment. At least three schools in virus-hit areas closed and teachers who live on farms were told to stay home. Hunts have already been suspended, and on Monday a pro-hunting group postponed a mass march - months in the planning - that had been set for next month to protest a proposed ban on fox-hunting with hounds. A major two-week military exercise to begin Friday was being hastily revised because it involved use of ground troops in an area close to an infection site. Hiking groups scrapped country walks and fishing streams were closed to anglers. Safari parks, zoos and nature reserves were closing or keeping animals susceptible to the disease - including rhinos, giraffes and elephants - well away from people. A rugby match between Wales and Ireland, set Saturday in Cardiff, Wales, may be called off because authorities are afraid Irish fans could bring the virus home with them.