The importance of immediate destruction in epidemics of foot and mouth disease.

Foot and mouth disease is still prevalent in many parts of the world, as emphasised by the recent devastating epidemic in pig farms in Taiwan. A discrete time mechanistic model has been used to describe the spread of infection in both this epidemic and the 1967 to 1968 epidemic in the UK. The force of infection and basic reproduction number are estimated and the sensitivity of these results to the distributions of both the latent and infectious periods of the disease is examined. Epidemic simulations were performed to evaluate the disease control policy whereby all herds are slaughtered on the same day as disease confirmation. These simulations showed that implementing this policy could have resulted in a dramatic reduction (of over 60 per cent) in the number of pig farms affected in the Taiwan epidemic. It is thus imperative that the necessary resources are available to implement this policy, should an outbreak occur.