FROM the moment a country is struck by foot and mouth disease, officials have just hours to react to save farmer鈥檚 livelihoods and avoid millions of animals being slaughtered. That鈥檚 the message rammed home by the most detailed examination yet of the foot and mouth epidemic that paralysed Britain last year.
Researchers who reconstructed the epidemic in forensic detail estimate that the number of infected farms would have been cut by 60 per cent, from 2026 to 793, if the government had banned animal movements immediately the disease was confirmed instead of three days later.
鈥淗alf the epidemic was seeded over those three days,鈥� says lead researcher Mark Woolhouse of the University of Edinburgh, who advised the government during the crisis.
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Woolhouse鈥檚 analysis is the most accurate yet at estimating what difference early action would have made. His team used government data on each case to reconstruct how the disease was transmitted from farm to farm. In 361 cases the source of infection is fairly certain. For the rest, the researchers made a best guess based on the proximity of infected farms (Proceedings of the Royal Society B, DOI:10.1098/rspb.2002.2191).
The approach differs from previous analyses, which take parameters such as the disease鈥檚 incubation time and plug them into a mathematical model. Woolhouse鈥檚 approach uses more details of the real epidemic, and so makes fewer assumptions. 鈥淵ou can include all the complicating factors you could never put into a model,鈥� says Matt Keeling at the University of Warwick, who has modelled the 2001 epidemic (New Scientist, 1 December 2001, p 34). This is significant because tiny details, such an infected sheep spreading the disease at a particularly busy market, can have huge consequences.
Such information allowed Woolhouse鈥檚 team to calculate that if a ban on the movement of livestock had been imposed the day the disease was confirmed, 20 February 2001, the final cull could have been reduced from 4,050,000 animals to around 1,620,000.
An earlier ban could also have halved the 拢3 billion cost to the government of controlling the disease, and cut the 拢5 billion loss to the rural economy and tourism.
The government, however, dismisses Woolhouse鈥檚 figures as an overestimate. It also argues that it could not have acted any faster than it did. 鈥淎 national ban was imposed as soon as it became clear that there was a national problem,鈥� a spokesman for the Department for Environment Food and Rural Affairs told New Scientist. But he did add that such a ban would be imposed immediately if any future outbreak occurred.