Oral immunisation of wild boar against classical swine fever: evaluation of the first field study in Germany

Abstract

The effectiveness of oral immunisation of wild boar against classical swine fever (CSF) was studied in a field trial in Lower Saxony for two years, from 1993 to 1995. This field study was performed in an area of ca. 270 km 2, belonging to three military training grounds. Wild boar in one range were uninfected, whilst the wild boar population of the other two ranges were infected with CSF virus. The animals were vaccinated with a bait vaccine. The immunisation procedure included a double vaccination with an interval of ≈14 days. This was followed by repeated vaccination campaigns at 6 monthly intervals. The rate of uptake of baits at feeding places was determined to be between 85 and 100%. The bait marker oxytetracycline could be detected in bone samples in 52.4–67.6% of hunted animals. The antibody prevalence reached 49–60.3% after immunisation. However, >50% of young boars did not feed on vaccine baits nor become immunised. Therefore, an intensive hunting of this age group is a necessary adjunct to the use of oral vaccination. After the third immunisation period, no virus was detected in the areas where oral immunisation took place.