In Switzerland sarcoptic mange is frequent in free-ranging wild carnivores but until recent years no cases had been recorded in wild ungulates. Since 2010, cases have been observed in wild boar in the cantons of Solothurn, Tessin and Thurgau. Here, we report the detection of mange-like skin lesions in wild boars by photo-trapping and the post-mortem findings in 6 culled animals presenting different stages of the disease. Potential sources of infection include mangy red foxes, outdoor domestic pigs and wild boars from surrounding countries. Disease spread in the wild boar population may become relevant not only for wildlife but also for domestic pig health in the future if piggeries' biosecurity is insufficient to prevent interactions with wild boar.
BackgroundSarcoptic mange has recently emerged in wild boar in Switzerland, raising the question of the origin of the infection. The main aim of this study was to assess the extent of exposure of the wild boar populations to Sarcoptes scabiei in Switzerland, prior to and after the detection of mange cases, to determine whether the mite has been recently introduced into the populations concerned. We performed a serological survey using a commercially available ELISA and 1056 archived blood samples of free-ranging wild boar from Switzerland. To facilitate the interpretation of the obtained data, we additionally estimated seroprevalence in wild boar populations of four other European countries (1060 samples), both from areas with confirmed clinical cases of mange and from areas without reported cases in wild boar. Lastly, we revised the evaluation of the commercial ELISA when used with wild boar sera.ResultsSeropositive reactions were observed for samples from all five countries and from 15 of the 16 study areas. The obtained apparent seroprevalences ranged from 0.0% (0/82; 95% confidence interval [CI]: 0.0–4.4) to 17.4% (8/46; 95% CI: 7.8–31.4). Wild boar from study areas with known clinical cases and those ≤60 kg were four times more likely to be seropositive than wild boar from areas without reported cases and > 60 kg, respectively. Optical density values did not differ between the two types of study areas among seropositive samples but were significantly lower among seronegative samples from areas without than from areas with clinical cases. No difference was observed between the two sampling periods in Switzerland. The revised ELISA specificity was 96.8% (984/1017; 95% CI: 95.5–97.7) when wild boar from areas without history of mange were considered truly negative.ConclusionsSeropositivity to S. scabiei is more frequent and occurs over a larger geographic range than expected. Data suggest that the parasite is endemic within the wild boar populations of Switzerland and other European countries but that its presence is not necessarily associated with disease occurrence. Extrinsic factors which trigger disease emergence in infected populations remain to be investigated. The applied ELISA represents a promising tool for future studies.Electronic supplementary materialThe online version of this article (10.1186/s12917-018-1430-3) contains supplementary material, which is available to authorized users.
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