Ecology of wildlife rabies in Europe

Abstract

1. The number of wildlife rabies cases has increased in Europe in recent years. We review the epizootiology of wildlife rabies in Europe, paying special attention to recent changes to the situation of two important vector species: the red fox and the raccoon dog. Red fox Vulpes vulpes has been the main vector of rabies since 1945, but the number and proportion of raccoon dog Nyctereutes procyonoides cases has rapidly increased during the past few years, particularly in north-eastern Europe. 2. The transmission rate (average number of susceptible animals infected by each rabid animal) is critical for rabies spread and is partly determined by population density. Both raccoon dogs and foxes live in pairs. Foxes also live in family groups. Pairs and groups share their territories. Home range size usually correlates negatively with population density. Fox home ranges are 50-1500 ha, those of raccoon dogs 150-700 ha. The threshold value for rabies spread among foxes is estimated to be 0.63 individuals/km 2 . Although fox density in eastern and northern Europe may be lower than this, the pooled density of foxes and raccoon dogs exceeds the threshold density. 3. Animal movements, especially dispersal of young, pose a risk for rabies spread. Although the likelihood of an epizootic is highest where fox and raccoon dog densities are highest, rabies may spread fastest where population densities are lower, because dispersal distances tend to correlate negatively with population density. 4. Oral vaccinations have been more effective in rabies control than culling foxes. Where two vector species exist, vaccination should be conducted twice a year, because most raccoon dogs disperse in autumn but some foxes do not disperse before mid-or late winter. 5. New rabies models, based on two vector species and their interaction, and which take into account the hibernation period of raccoon dogs, are needed for north-eastern Europe.

Rabies in the Arctic Fox Population, Svalbard, Norway

“…The fox density in one area of Svalbard, in Adventdalen and Sassendalen (900 km 2 ), has been estimated to 0.1-0.15 animals per km 2 (Eide, 2002), considerably lower than in other arctic regions with arctic foxes of the inland ecotype. In Sweden, the density of red foxes (Vulpes vulpes) is estimated to be 0.2-0.4 foxes per km 2 , which is regarded as too low for the generation of rabies epizootics (Holmala and Kauhala, 2006). Thus, the even-lower and more-stable fox population density in Svalbard can explain the lack of reported epizootics.…”

Wild carnivores as source of zoonotic helminths in north-eastern Italy

“…Both canids can host many species of parasites infecting foxes. The raccoon dog is a vector of rabies (Holmala & Kauhala 2006) and parasites particularly of Echinococcus multilocularis, as showed by some infected raccoon dogs found in Germany, of Sarcoptes scabiei (Shibata & Kawamichi 1999;Ninomiya & Ogata 2005), and of Trichinella spp. (Oksanen et al, 1998;Oivanen et al, 2002).…”

Rabies in Northeastern Europe—the Threat From Invasive Raccoon Dogs

“…Botvinkin et al (1985) demonstrated in the laboratory that small rodents would not fall ill during hibernation, but would show rabies signs shortly after becoming active again. A similar effect is expected for rabies incubation in hibernating raccoon dogs (Cerkasskij, 1980;Holmala and Kauhala, 2006).…”