Successful intervention in a disease outbreak in the endangered Iberian lynx: what can we learn?

Global biodiversity is increasingly under threat and species loss has prompted the argument that our natural world is experiencing a sixth major extinction event (PimmB Woodroffe, 2000; Treves & Karanth, 2003; Whitman et al., 2004). Parasites are increasingly linked to population impacts in wild felid and canid species (Pedersen et al., 2007). Many predator species exist in small and fragmented populations, vulnerable to stochastic events and other ongoing sources of population loss, which can drive them locally, if not globally, extinct. The Iberian lynx is a key example of an imperiled predator and is currently the most endangered felid in the world (Nowell & Jackson, 1996; Baillie, Hilton-Taylor & Stuart, 2004). This species may lose the survival battle without intense and continued conservation intervention. In their paper, Lopez et al. (2009) provide an excellent example of endangered species management, which demonstrates the importance of long-term population monitoring programs and the effectiveness of careful intervention design. Through their monitoring program, the authors identify the emergence of feline leukemia virus (FeLV) in the core population of Iberian lynx on the Iberian Peninsula. This pathogen is commonly found in domestic cats, which are considered the primary host (Arjona et al., 2007). While previous low-level FeLV exposure had been identified in the Iberian lynx population before the 2007 outbreak (Luaces et al., 2008; Meli et al., 2009), no associated mortality or other impacts had been identified. Then, inexplicably, FeLV emergence in 2007 causes an outbreak with mortality levels that threaten the survival of the species. Viral sequence from the 2007 outbreak is distinct from previous infections in the population but consistent with transmission from locally infected cats (Meli et al., 2009). In response to the outbreak, a FeLV control program is undertaken by the authors and other partners, which utilizes a test, removal and vaccination approach in Iberian lynx coupled with reduction of the sympatric feral cat population. It is successful and FeLVassociated mortality in the Iberian lynx ceases. What can we learn from the approach taken by Lopez and colleagues? Firstly, intervention for the Iberian lynx disease outbreak is designed and implemented through a partnership approach between many national stakeholders, project participants and experts. Often in wildlife management crises, consultation and inclusiveness of stakeholders is avoided in order to streamline processes and expedite action. But this can backfire when partner agencies and stakeholders are required in downstream management activities. This paper serves as a reminder that wildlife management is better implemented inclusively rather than exclusively. Secondly, this study demonstrates the dynamic and unpredictable nature of pathogen invasion outcomes in a population. In this case, FeLV invasion in the population was not identified as an important problem but this changed dramatically in the 2007 outbreak. This highlights the danger of defining the threat level of a pathogen for a species. It is becoming clearer that pathogen behavior can vary widely between species, and within and between populations over space and time. A number of factors influence pathogen invasion outcomes as they operate and interact at the level of the host, pathogen and/or the environment, which can influence host susceptibility and/or pathogen virulence and change the nature of an outbreak in a susceptible host population (Hudson et al., 2002). Thus, as in forensic sciences, we are reminded to be cautious with ‘pathogen profiling’ or reliance on expected behavior of a pathogen, as seen here in the divergent nature of FeLV invasion in Iberian lynx or for example, distemper outbreaks in African wild dogs in Botswana (Alexander et al., 1996; Alexander et al., 2008)