The eradication of foot-and-mouth disease: a parallel problem.

Poliomyelitis and foot-and-mouth disease (FMD) can both be prevented by vaccination. The vaccines are highly effective but they differ in that, whereas in most countries attenuated viruses have been used to control poliomyelitis, FMD vaccines are prepared from the virulent viruses. The reasons for choosing inactivated vaccines for FMD are (i) the demonstration several decades ago that a virus which was attenuated for one species could be virulent for another and (ii) the great antigenic variability of the virus. This has meant that the viruses to be used for vaccination have to "match" those occurring in the field. It also means that they should only be handled under strict conditions of containment.