Abstract
Canine distemper virus (CDV) has recently emerged as an extinction threat for the endangered Amur tiger (Panthera tigris altaica). CDV is vaccine-preventable, and control strategies could require vaccination of domestic dogs and/or wildlife populations. However, vaccination of endangered wildlife remains controversial, which has led to a focus on interventions in domestic dogs, often assumed to be the source of infection. Effective decision making requires an understanding of the true reservoir dynamics, which poses substantial challenges in remote areas with diverse host communities. We carried out serological, demographic, and phylogenetic studies of dog and wildlife populations in the Russian Far East to show that a number of wildlife species are more important than dogs, both in maintaining CDV and as sources of infection for tigers. Critically, therefore, because CDV circulates among multiple wildlife sources, dog vaccination alone would not be effective at protecting tigers. We show, however, that low-coverage vaccination of tigers themselves is feasible and would produce substantive reductions in extinction risks. Vaccination of endangered wildlife provides a valuable component of conservation strategies for endangered species.
Highlights
Canine distemper virus (CDV) has recently emerged as an extinction threat for the endangered Amur tiger (Panthera tigris altaica)
Infectious diseases are increasingly recognized as an extinction threat for endangered carnivores, and viral pathogens, those linked with domestic dogs (Canis familiaris), have been the cause of major declines in several populations [2]
CDV was first detected as the cause of death in Amur tigers in 2003, with subsequent cases confirmed in 2010 [6, 7]; population viability analyses showed that CDV increased the 50-y extinction probability of small populations to over 50%, an increase of up to 65% [8]
Summary
Infectious diseases are increasingly recognized as an extinction threat for endangered carnivores, and viral pathogens, those linked with domestic dogs (Canis familiaris), have been the cause of major declines in several populations [2]. Our first objective was to generate and evaluate epidemiological evidence to determine the likely relative importance of domestic dogs and wild carnivore hosts as sources of CDV infection for Amur tigers in the Primorskii Krai region of Russia. Of the 32 dogs in the most remote survey community, all had been born there, and none had traveled to other settlements; we detected antibodies in four of the five unvaccinated dogs sampled, including a 12-mo-old pup This population is far too small to maintain the pathogen [17], so the most plausible explanation for recently infected individuals is that wildlife constitutes an important source of CDV infection for dogs, challenging a widely held view that the epidemiological cycle is dominated by dog-to-wildlife transmission. The results from the single dog suggest that a distinct epidemiological cycle is occurring there
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