Distemper, extinction, and vaccination of the Amur tiger

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.

Paradoxes and synergies: optimizing management of a deadly virus in an endangered carnivore

“…Our simulation results found that relatively high levels of vaccination were required to reduce impacts of FeLV in panthers, in contrast to studies in other endangered species (7, 9). However, here we are investigating a pathogen with a long duration of infectiousness and lack the advantages of distinct corridors between panther sub-populations for reducing required levels of vaccination.…”

“…Our simulation results found that relatively high levels of vaccination were required to reduce impacts of FeLV in panthers, in contrast to studies in other endangered species (7,9).…”

“…However, here we are investigating a pathogen with a long duration of infectiousness and lack the advantages of distinct corridors between panther sub-populations for reducing required levels of vaccination. It is therefore unsurprising that panthers would require higher levels of FeLV population vaccination than was found, for example, for rabies vaccination in Ethiopian wolves (7) or canine distemper virus vaccination in Amur tigers (9). However, we also did not assume the presence of preexisting population immunity prior to proactive vaccination, and some degree of population immunity likely already exists in panthers, given ongoing exposures (4).…”

“…Models allow the ethical testing of a wide range of different management approaches and can reveal unexpected consequences of disease control interventions (6). Models have been used to optimize disease management protocols in a variety of free-ranging wildlife species of conservation concern, including Ethiopian wolves (7), chimpanzees (8), and Amur tigers (9). Further, models can serve the important function of balancing the realities of fieldwork with ideal disease control protocols to provide practical, effective guidance for wildlife managers (e.g., 10, 11).…”

Bioaccumulation of Pathogen Exposure in Top Predators

“…Spillover may result in catastrophic consequences to the new host, resulting in significant economic [4,5] or conservation [6][7][8][9] impacts and major threats to wildlife survival and biodiversity; for example, distemper in African lions (Panthera leo) [10], and plague and distemper in blackfooted ferrets (Mustela nigripes) [11,12]. Recent studies have indicated, however, that crossspecies transmission frequently occurs without substantial population-level impacts to the recipient host [13,14].…”