Fatal Sarcoptes scabiei and Demodex sp. co-infestation in wolves (Canis lupus) at the Białowieża National Park, Poland – is it a consequence of climate change?

Abstract

Introduction: In winter 2021/2022, a wolf population in the primeval Białowieża Forest in Poland was struck by an outbreakof severe mange caused by mixed infestations of Sarcoptes and Demodex mites. We present an epidemiological analysis of thismange which caused significant morbidity and mortality. Material and Methods: Ten sites known for wolf activity weremonitored by camera trapping. A diagnostic necropsy and testing of a young wolf was performed to determine the causes of death.Results: Five young wolves with severe alopecia of the entire body and some other individuals with minor to medium mangelesions were identified by the camera surveillance. The necropsy of the carcass revealed emaciation, dehydration and anaemia withstarvation as the cause of death, likely attributable to severe infestation with Sarcoptes scabiei and Demodex sp. mites. Rabies andinfections with Borreliella sp., Anaplasma sp., Ehrlichia sp., Francisella tularensis, Babesia sp. and tick-borne encephalitis viruswere excluded by specific tests. Conclusion: The described analysis is the first documented co-infestation of this kind in wolves.The outbreak coincided with very mild winter conditions with a high average minimum temperature, which may have favouredmite survival outside the host, and light snowfall, which may have influenced the wolves’ ability to hunt. Other potential driversof the outbreak could be the large proportion of wetland terrain, increasing number of wolves in the area and anthropogenic pressureon their habitats including the migration crisis at the Polish–Belarusian border and the increased presence of military and borderforces, even despite the relief from the anthropogenic pressure from tourism due to the COVID-19 lockdown.