Residual foot-and-mouth disease virus antibodies in French cattle and sheep six years after the vaccination ban

A serological survey was carried out on French cattle to establish a refere nce pattern of residual vaccine antibodies and non-specific reactions again st the foot-and-mouth disease virus 6 years after the ban on vaccination an d in the absence of any foot-and-mouth disease outbreak. Most of the multi- vaccinated cattle still displayed high titres of antibodies and up to 50% o f those which had received a single injection still had antibodies. Non-spe cific reactors were also recorded among animals born during and after 1991. Most of them displayed low titres close to the threshold. Sheep were also tested and, as for cattle, 4.6% of non-specific reactors were recorded, wit h titres close to the threshold for two-thirds of them. As part of these an imals have been resampled and retested, sera revealed negative confirming t hat these animals are true non-specific reactors. Serological testing as a mean of FMD control should take these facts into account.