Sarcoptic mange in wild ruminants in Spain: solving the epidemiological enigma using microsatellite markers

BackgroundIn Spain, sarcoptic mange was first described in native wildlife in 1987 in Cazorla Natural Park, causing the death of nearly 95% of the local native population of Iberian ibex (Capra pyrenaica). Since then, additional outbreaks have been identified in several populations of ibex and other wild ungulate species throughout the country. Although the first epizootic outbreak in wildlife was attributed to the introduction of an infected herd of domestic goats, the origin and the cause of its persistence remain unclear. The main aims of this study are to understand (i) the number of Sarcoptes scabiei strains circulating in wild ruminant populations in Spain, and (ii) the molecular epidemiological relationships between S. scabiei and its hosts.MethodsTen Sarcoptes microsatellite markers were used to characterize the genetic structure of 266 mites obtained from skin scrapings of 121 mangy wild ruminants between 2011 and 2019 from 11 areas in Spain.ResultsSeventy-three different alleles and 37 private alleles were detected. The results of this study show the existence of three genetic strains of S. scabiei in the wild ruminant populations investigated. While two genetic clusters of S. scabiei were host- and geography-related, one cluster included multi-host mites deriving from geographically distant populations.ConclusionsThe molecular epidemiological study of S. scabiei in wild ruminants in Spain indicates that the spreading and persistence of the parasite may be conditioned by host species community composition and the permissiveness of each host population/community to the circulation of individual strains, among other factors. Wildlife-livestock interactions and the role of human-driven introduction or trade of wild and domestic animals should be better investigated to prevent further spread of sarcoptic mange in as yet unaffected natural areas of the Iberian Peninsula.

Automated summary

The study in Spain reveals the existence of three genetic strains of Sarcoptes scabiei in wild ruminant populations, with two clusters being host- and geography-related, and one cluster consisting of multi-host mites from geographically distant populations. This suggests that the spread and persistence of the parasite may be influenced by host species composition and the permissiveness of each host population to different strains, among other factors. Investigating wildlife-livestock interactions and human-driven introductions or trades of wild and domestic animals is crucial to prevent further spread of sarcoptic mange in unaffected natural areas of the Iberian Peninsula.