First report of interspecific transmission of sarcoptic mange from Iberian ibex to wild boar

Abstract

Background Sarcoptic mange is a globally distributed parasitic disease caused by the burrowing mite Sarcoptes scabiei. This mite has a certain degree of host specificity, although interspecific transmission can occur among phylogenetically related species or through prey–predator mediated exposure. In 2018, a wild boar (Sus scrofa) with lesions compatible with sarcoptic mange was hunted in Ports de Tortosa i Beseit Natural Park (PTB, north-eastern Spain), where an active epizootic outbreak of sarcoptic mange is affecting Iberian ibexes (Capra pyrenaica) since 2014. Methods A complete necropsy, skin scrapings and skin digestions with hydroxide potassium were performed to confirm the diagnosis. Routine histopathological analysis, toluidine blue staining and immunohistochemistry were used to characterize the lesions and the inflammatory infiltrate. Finally, 10 specific S. scabiei microsatellites were molecularly genotyped through polymerase chain reactions in mites obtained from the affected wild boar. For phylogenetic comparison, mites obtained from sympatric Iberian ibexes and allopatric wild boars and Iberian ibexes from southern Spain were analysed. Results Sarcoptes scabiei was visually and molecularly identified in the infested wild boar from PTB, causing skin lesions with dermal inflammatory infiltrate rich in T and B cells, which indicate an adaptive immune response. Three S. scabiei genetic clusters were identified: one included mites from southern Iberian ibexes, another included mites from southern wild boars, and a third one distinctively grouped the wild boar from PTB with the sympatric ibexes. Conclusions To the authors’ knowledge, this is the first reported case of sarcoptic mange in wild boar in Spain and the first documented case of S. scabiei cross-transmission from a wild ruminant host to a wild boar. The wild boar presented an ordinary scabies type reaction, which is typical of the self-limiting infestations reported in other cases of interspecific transmission. Graphical abstract

Ivermectin Plasma Concentration in Iberian Ibex (Capra pyrenaica) Following Oral Administration: A Pilot Study

“…The rapid drop of plasma IVM concentration in Iberian ibex after a single oral dose found in this study, and the lack of published results on therapeutic trials with oral IVM in scabietic free-ranging individuals suggest caution in promoting the mass delivery of IVM medicated pellets as a measure to efficiently control sarcoptic mange at the individual and population level in this wild caprine. The epidemiological effects of partially ineffective treatment strategies could even be opposite, by lengthening the infective stage of the individuals affected by sarcoptic mange and therefore increasing the dissemination and spread of the disease (25), potentially to other mammal species too (12,49). Moreover, aspects such as the proportion of the target population actually receiving the treatment, the access to the drug by non-target species, and the environmental effects of the massive release of IVM in the environment, are still in need to be thoroughly investigated and controlled (8,10).…”

“…Nevertheless, no studies support the actual effectiveness of this common practice. In fact, essential gaps in knowledge need to be filled before considering oral mass treatments as a possible control measure for the management of sarcoptic mange in free-ranging Iberian ibex and other susceptible wild ruminants (11,12). Among the knowledge gaps to fill before implementing any in-field treatment, the pharmacokinetics of orallyadministered candidate acaricides in the target hosts are crucial.…”

Subcutaneous Ticks in Wild Carnivores: Any Host-Related Differences?

“…Dwużnik et al [ 11 ] advanced the hypothesis of a mechanism generated by the host-hyperimmune response during the first days after the tick attachment, leading to a deep penetration of the hypostome through the hypodermic layers, and its progressive embedment (also called “sinking”) underneath the skin, impeding it to resurface. As already shown for other ectoparasites, such as the mite Sarcoptes scabiei causing sarcoptic mange, different host species can have different immune responses [ 29 , 30 , 31 , 32 ] with various degrees of clinical signs depending on the age, sex, and body condition, as it may happen with ticks. In particular, red foxes would be less effective at countering sarcoptic mange (frequently showing severe skin lesions) due to a lack of memory T-cells after the contact with Sarcoptes mites [ 29 , 33 ], which might also explain the higher incidence of SCT in this species.…”

Zoonotic Episodes of Scabies: A Global Overview

“…Beyond the literature, the authors have personal experience that ZS is not uncommon among hunters and gamekeepers in areas of Central and Southern Europe where mountain-dwelling ruminants are endemically infected with sarcoptic mange [44,47]. However, to the authors' knowledge, no ZS cases have been reported in wild boar hunters, although the disease is observed in wild boar throughout Europe [13,64,65]. Delafond and Bourguignon [7] mention a single ZS case following contact with the skin of a scabietic wild boar in Germany.…”

“…Transmission from humans to animals has also been documented in mountain gorillas [11]. Furthermore, S. scabiei cross-transmission between different animal species has been reported in more than 50 species [12,13], under natural or human-driven conditions, highlighting the pronounced epidemiological plasticity of this ectoparasite.…”