Endemic and widespread exposure to Sarcoptes scabiei in the threatened Iberian lynx (Lynx pardinus).

The Iberian lynx (Lynx pardinus) is one of the most endangered feline species in the world, and different infectious diseases, such as feline leukaemia virus, Aujeszky's disease or sarcoptic mange, have long posed a significant threat to its survival. Severe clinical disease caused by Sarcoptes scabiei have been reported in the Iberian lynx, however, the extent of S. scabiei infestations/infections in this species is unknown. In this context, we aimed (1) to assess S. scabiei exposure in Iberian lynx populations, and (2) to identify potential risk factors associated with parasite exposure. Between 2010 and 2023, 615 Iberian lynxes from captive (n = 270) and free-ranging (n = 345) populations were sampled across the Iberian Peninsula. Antibodies against S. scabiei were found in 15.4 % (95/615; 95 %CI: 12.8-18.5) of the Iberian lynxes using an in-house indirect enzyme-linked immunosorbent assay (ELISA) based on the immunodominant recombinant antigen Ssλ20ΔB3. Seropositive individuals were found in the three major free-range areas under study, such as the Central, Southern and Southwestern Iberian Peninsula. A significantly higher seroprevalence was detected in free-ranging (18.0 %) than in captive (12.2 %) lynxes. Logistic regression analysis identified "age" and "free-range sampling area" as potential risk factors for parasite exposure. Anti-S. scabiei antibodies were detected in lynxes sampled in each year of the study period, except for 2023, including five free-ranging yearlings sampled in 2012, 2019, 2020 and 2022. Our results confirm that both free-ranging and captive populations are naturally exposed to the parasite. The detected seroprevalence indicates moderate S. scabiei exposure of the Iberian lynx and provides evidence of endemic, widespread, and heterogeneous circulation of the parasite in lynx populations over the last two decades, which could be of animal health and even conservation concern. Additional studies are needed to assess the impact of S. scabiei in this vulnerable felid species.