Rabies in particular appears to be a significant threat to Ethiopian wolf populations of all sizes whereas canine distemper was of little importance in determining wolf population persistence. The impact of rabies was particularly severe in small populations (25 – 50 individuals) where any additional mortality caused substantial increases in population extinction probabilities over 50 years. Thus, any reduction in disease incidence in the dog population has a beneficial effect on wolf population persistence and is especially important for the persistence of five remnant populations estimated to harbour fewer than 50 individuals.

This model also suggested that vaccination of as few as 20-40% of wolves against rabies might be sufficient to eliminate the largest epidemics and therefore protect populations from the very low densities which makes recovery unlikely. Exploration of the effect of variation in vaccine-induced immunity and population coverage patterns on wolf population persistence, suggested that in large (250 animals) populations of wolves, vaccines inducing 3 or mroe years immunity reduced extinction probabilities from 12% to 2% over 50 years with coverage of as little as 20-30% of juvenile recruitment. In smaller populations (25-50 animals) this relationship was linear. Short-acting vaccines (1 year) required a doubling of coverage levels to achieve the same reduction of extinction probabilities. Population persistence was maximized when vaccination effort was concentrated within selected packs, rather than evenly dispersed over the entire population. Such a strategy ensures a core of behaviourally functional breeding packs is preserved able to contribute sooner to population recovery

Relevant publications

Haydon, D.T., M.K. Laurenson & C. Sillero Zubiri. 2002. Integrating epidemiology into population viability analysis: the risk posed by rabies and CDV to Ethiopian wolves Conservation Biology 16:1372-1385

Haydon, D. T., S. Cleaveland, L.H. Taylor & M.K. Laurenson 2002. Identifying reservoirs of infection: a conceptual and practical challange. Emerging Infectious Diseases 8:1468-1473.