Update on oral vaccination of foxes and raccoon dogs against rabies
An assessment of a report issued by the European Commission in 2002 is presented about the oral vaccination of foxes against rabies, as well as additional topics such as the rabies aetiology and its occurrence in Europe, the target species for oral vaccination, i.e. foxes and raccoon dogs, the oral vaccines available and their thermostability, rabies surveillance and monitoring, and the recent international guidelines for rabies surveillance are discussed. Foxes are the only known reservoir for rabies in Europe, and raccoon dogs are important transmitters, while other carnivores play a less important epidemiological role. The demographic expansion of raccoon dogs and their movements after hibernation are risk factors for rabies recurrence. The combined densities of foxes and raccoon dogs, which often share the same habitats, could allow rabies epizootics to persist. The epidemiological role and the pathogenesis of rabies in raccoon dogs and other carnivores must still be clarified. Four vaccines are authorised in the EU and their effectiveness is proven to successfully contribute to rabies elimination. Experimental and field evidence shows that climatic and weather conditions may impact on bait casings and vaccine stability. Data on the stability of vaccine baits under different field conditions should be provided. It is recommended that bait should keep its integrity at the release point. Because of bait stability issues, the season most appropriate for implementing oral rabies vaccination or a heat-stable vaccine should be considered. Rabies surveillance and monitoring of vaccination, based on assessment of bait uptake and seroconversion in host species, are important tools for the evaluation and adjustment of vaccination campaigns, although alternatives to tetracyclines as biomarkers should be developed. Oral immunisation by vaccine baits has proven to be successful in eliminating terrestrial wildlife rabies, but long-term strategy, temporal continuity of vaccination and cross-border cooperation are needed and recommended.