Elimination of terrestrial rabies in Western European countries.

Since the late 1930s, the red fox (Vulpes vulpes) has been the main vector of rabies in Europe. Practically, decimation of fox population did not prevent the spread of the disease. The only efficient method to control wildlife rabies consisted in using oral vaccination by depositing vaccine baits containing a capsule or a plastic sachet filled with an attenuated anti-rabies liquid vaccine throughout fox habitats. Several live virus vaccines have been and are currently being used: the SAD B19 and SAD P5/88 are rabies strains attenuated in cell culture, the SAG1 and SAG2 strains are apathogenic mutants of an already attenuated rabies strain, and the VRG vaccine is an attenuated vaccinia virus recombinant coding for the rabies glycoprotein gene. These vaccines have different residual pathogenicity. SAG1 and SAG2 are pathogenic only for suckling mice inoculated by intracerebral and oral routes. VRG presents absolutely no rabies risk to humans and the environment and the residual pathogenicity of the vaccinia vector virus is very low even for humans. Other parameters such as the thermostability of the vaccine and the melting point of the bait casing are of utmost importance to guarantee the success of oral vaccination campaigns. Additionally, VRG is the only vaccine that did not interfere with maternal immunity in fox cubs, an important issue for spring campaigns. Successes and failure of national programmes confirm that whatever the ecological conditions, the same rules must be strictly followed to ensure the success of rabies elimination programmes: (i) considering the strategy, any rabies vaccination programme must be organised with the support of a national scientific team specially designated for the task that will have to apply the only methods that have already been proved successful elsewhere in Europe, including rabies surveillance, bait distribution calendar and pattern, and monitoring of this distribution; (ii) vaccination must be pursued for at least two years after the last reported case of rabies in the area; (iii) the choice of a low cost but poorly efficient and poorly stable vaccine does not prove to be cost-beneficial for successful elimination of rabies. Several European countries have become rabies-free: Belgium, Luxembourg, France, Italy, Switzerland, Finland and the Netherlands. Since the European Union is going comprise 25 countries from May 2004, all the scientific knowledge is available for establishing efficient and adapted oral programmes aimed at eliminating terrestrial rabies from this area.