Sarcoptic mange outbreak decimates South American camelid populations in San Guillermo National Park, Argentina

Abstract

Sarcoptic mange epidemics can devastate wildlife populations. In 2014, mange was first detected in vicuña ( Vicugna vicugna ) and guanaco ( Lama guanicoe ) in San Guillermo National Park (SGNP), Argentina. This study characterized the potential source and the impacts of the outbreak in 2017–2019. Transect surveys indicated a sharp decrease in the density of live vicuña and guanaco by 68% and 77%, respectively, from May 2017 to June 2018. By April 2019 no vicuña or guanaco were recorded on transect surveys, suggesting a near-extinction at the local level. Clinical signs consistent with mange (e.g. intense pruritus, hyperkeratosis, alopecia) were observed in 24% of live vicuña (n = 478) and 33% of live guanaco (n = 12) during surveys, as well as in 94% of vicuña carcasses (n = 124) and 85% of guanaco carcasses (n = 20) opportunistically examined during the study period. Histological examination (n = 15) confirmed sarcoptic mange as the cause of the cutaneous lesions. Genetic characterization revealed that Sarcoptes scabiei recovered from seven vicuña (n­ = 13) and three guanaco (n = 11) shared the same genotype, which is consistent with a single source and recent origin of the epidemic. A governmental livestock incentive program introduced llama ( Lama glama ) in areas adjacent to SGNP in 2009, some of which reportedly had alopecic scaling consistent with sarcoptic mange. We hypothesize that the introduction of mange-infected llama may have triggered the outbreak in wild camelids which has now put them at a high risk of local extinction. This unprecedented event highlights that the accidental introduction of disease may be underestimated at the onset yet can have devastating effects on native ungulate populations with potentially profound effects at the community and ecosystem levels.

Sarcoptic mange outbreaks in vicuñas (Cetartiodactyla: Camelidae): A scoping review and future prospects

“…Likewise, the high density of vicuñas has been hypothesized as a key factor in the spread of contagious disease between healthy and sick animals in wild unmanaged populations (Ferreyra et al., 2022). (ii) The social and gregarious behavior of camelids facilitates direct transmission between individuals (Ferreyra et al., 2022). (iii) Vicuñas co‐occur and share habitat with infected llamas and alpacas, which are widely distributed throughout the Andean mountains and at high population densities (Ruíz, 2016).…”

“…), as has been reported in other wild ungulates (Iacopelli et al., 2020) and overall host species (Escobar et al., 2022). Likewise, the high density of vicuñas has been hypothesized as a key factor in the spread of contagious disease between healthy and sick animals in wild unmanaged populations (Ferreyra et al., 2022). (ii) The social and gregarious behavior of camelids facilitates direct transmission between individuals (Ferreyra et al., 2022).…”

“…Sarcoptic mange in vicuñas causes erythema, intense pruritus, alopecia and severe skin lesions (thick, fissured, lichenified and crusted), leading to poor body condition, difficulty in movement and feeding, increased vulnerability to predators and even death. Lesions appear on the limbs, abdomen, chest, axillae, perineum and head (Gomez‐Puerta et al., 2013; Unzueta, 2018; Castillo et al., 2019; Ferreyra et al., 2022; Figure 2). Histopathologically, sarcoptic mange in vicuñas is described as dermatitis characterized by hyperkeratosis, parakeratosis, hyperplasia of sebaceous glands, absence of hair follicles and presence of an inflammatory infiltrate with a predominance of macrophages, plasma cells, neutrophils and eosinophils (Aráoz et al., 2016; Medina et al., 2021).…”

“…On the other hand, Ferreyra et al. (2022) found that vicuñas were more likely to have advanced stages of the disease in February (summer‐wet), compared to May or September.…”

“…Mange has also been reported in Chile as an early threat in vicuñas ( Vicugna vicugna ) and guanacos ( Lama guanicoe ), the two wild SACs (Montecino‐Latorre et al., 2020). Mange was further responsible for a sharp decline of vicuña and guanaco populations in a protected area of Argentina (Ferreyra et al., 2022). In Peru, this disease is considered a problem for some vicuña populations (Gomez‐Puerta et al., 2021).…”