YELLOWSTONE PATHOLOGY SKIN
Infected animals spend considerable amounts time scratching, which detracts from other activities including resting or effective hunting.Īlthough it is difficult to estimate, the energetic costs of mounting an immune response, both to the mites and to fighting secondary infections associated with skin damage must also drain resources from infected individuals. Infected individuals that suffer from hair-loss must expend much more energy to thermoregulate and keep sufficiently warm during winter months. How does mange affect Yellowstone's wolves? This suggests that the 'resistant' individuals that made it through the initial epidemic have gone on to populate the older age classes within the population, and thus it is primarily the young animals now that progress to more severe infections. Since some of our other analyses suggest that previous infection is not protective against re-infection, we believe this pattern is driven by the frailty effect. This pattern is consistent with either acquired immunity or a "frailty effect" where particularly susceptible individuals (due to genetics or general condition) are selected against early on in the epidemic.
One such change is that the age profile of severely infected individuals is shifting towards younger animals (Figure 8). However, we are seeing some patterns of infection that suggests the dynamics of the infection may be changing now that mange has been circulating within our population for some time. While this analysis is ongoing, it appears as though there are no significant patterns for age, sex, coat-color, or social status. This prompted us to ask: are there attributes of individuals or packs that might predispose them towards higher risk, greater severity, or longer duration of infection? The risk, severity, and duration of infection with mange are highly variable within Yellowstone's wolf population (Figure 7).
Individuals are scored as either uninfected or as class 1-3 (Figure 3) based on visible lesions and scratching behavior. Thus, our research revolves around tracking the appearance, spread, and recovery from mange-induced hairless lesions.Įach month, field crews attempt to observe or photograph all radio-collared individuals and their pack mates within Yellowstone National Park for the purpose of scoring infection status. Unlike most infectious diseases, mange causes obvious visible symptoms of infection. Sarcoptes scabiei has a broad host range, affecting numerous species including wolves, coyotes, foxes, members of the cat family, bears, wombats, chamois, ibex, and humans. Some studies have found evidence for limited, short-term immunity following recovery. Morbidity and mortality vary among species and individuals and is partly based on regional climate. Sarcoptes scabiei burrows into its host's epithelium and triggers an allergic reaction that causes severe itchiness, resulting in the thickening of skin, hair loss, and in secondary infections. Sarcoptes scabiei is primarily transmitted through direct contact, although the mite can survive for short periods of time off a host and may be spread through contact with contaminated bedding or feeding sites. By the early winter of 2007, mange had invaded the park's wolves (Fig 1 & 2). Wolves were reintroduced in 19 to Yellowstone National Park, and mange began appearing in wolves outside of Yellowstone in 2002. Sarcoptes scabiei, the mite that causes the skin infection known as sarcoptic mange, was introduced to the Greater Yellowstone Ecosystem as a biological control agent aimed at eliminating wolves during the predator control era in the early 1900s.Īlthough the mite is globally distributed and was at least present throughout parts of Canada in the early 1900s, to date, we have no evidence that it was locally present prior to its release by state veterinarians.įollowing the eradication of wolves from the ecosystem in the 1930s, mange is thought to have persisted within the regional furbearer populations (coyotes, foxes, etc.). Trend-lines for the total population (black) and infected subset (red) are displayed. Age distribution of class 2/3 mangy individuals (red) versus the total population (black).
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