The livestock population of Great Britain has been free from several of the most serious epidemic diseases since the late 19th century (rinder-pest, contagious bovine pleuropneumonia); others occur infrequently following introduction from abroad (foot-and-mouth disease (FMD), swine fever, swine vesicular disease (SVD); and the endemic diseases such as bovine tuberculosis and brucellosis are subject to successful eradication programmes.
On first examination the risk from exotic disease appears to lessen from year to year. The incidence of FMD has declined dramatically in Europe with the introduction of effective vaccination and slaughter policies and FAO/OIE programmes creating protective vaccination buffer zones in the east. Again within the European Community consideration is being given to a common policy to eradicate swine fever from all member States. However, a number of factors operate against these encouraging trends.
a. The relaxation of international trade barriers to the movement of live animals and animal products. It is essential within this framework to ensure that our animal health safeguards are preserved as far as possible against the introduction of disease from either member States or into the Community from third countries.
b. Pressures from the industry increase for the importation of livestock, semen or embryos to expand the gene pool within breeds.
c. The pyramidal structure of the industry — particularly the pig and poultry industry — increases the risk of dissemination of any disease agents introduced.
d. Larger, more intensive units reduce individual animal observation allowing symptoms of disease to remain undetected for longer periods and hence outbreaks to be more explosive when they occur.