Molecular Evidence of Canine Distemper Virus Circulation in Red Foxes and Golden Jackals from Western Romania

Canine distemper virus (CDV) is a highly contagious multi-host pathogen that poses a significant threat to both domestic and wild carnivore populations. The increasing overlap between wildlife habitats, peri-urban environments, and domestic animal populations has raised concerns regarding the epidemiological role of wild canids in maintaining and disseminating CDV. This study investigated the occurrence of CDV infection among free-ranging wild canids from western Romania. Brain tissue samples collected from 64 free-ranging wild canids, including 38 red foxes (Vulpes vulpes) and 26 golden jackals (Canis aureus), were initially screened using a commercial immunochromatographic antigen detection assay. Positive samples were subsequently subjected to molecular confirmation by real-time reverse transcription polymerase chain reaction (RT-qPCR). CDV antigen was detected in 16 of the 64 investigated animals (antigen-positive proportion: 25.0%), including 12 red foxes (31.6%) and 4 golden jackals (15.4%). All antigen-positive samples were subsequently confirmed by RT-qPCR, demonstrating the presence of CDV RNA in the screened-positive subset. Since molecular testing was performed only on antigen-positive samples, these proportions should not be interpreted as molecular prevalence estimates. Viral RNA was confirmed in all antigen-positive samples by RT-qPCR, providing molecular evidence of CDV infection in opportunistically sampled wild canids. Although a higher antigen-positive proportion was observed in red foxes, no statistically significant association was identified between host species and CDV positivity (χ² = 2.16, p = 0.142). These findings provide molecular confirmation of CDV infection in opportunistically collected rabies-negative wild canid carcasses from western Romania. Although the study demonstrates the presence of CDV in both investigated species, the sampling strategy does not allow estimation of population-level occurrence or broader epidemiological inference. Continuous molecular surveillance integrating wildlife, domestic animals, and environmental monitoring is warranted to improve understanding of CDV epidemiology and transmission dynamics in southeastern Europe within a One Health framework.