Clinical form of babesiosis caused by Babesia canis in Polish foxes (Vulpes vulpes)

The red fox (Vulpes vulpes) is known to be a reservoir host of various vector-borne protozoan parasites. However, the impact of infections caused by Babesia canis on the health status of the red fox remains unknown, and research on this topic conducted on fox populations in Poland and worldwide has been fragmentary. It is known that these animals can become infected with Babesia canis, but it is unclear whether a clinical form of the disease can develop in them. This study aimed to present for the first time the cases of clinical babesiosis in foxes in Poland. The observations covered four foxes aged 3-6 years with apathy, anemia, brown color of urine and thrombocytopenia. The PCR and sequencing results confirmed that all the animals had been infected with Babesia canis protozoa. The diagnosis of clinical cases of babesiosis due to B. canis in foxes from this region of Europe suggests a contribution of red foxes to the establishment of this animal species as a new reservoir of B. canis. These animals may play a role as a host for B. canis, and previously unexposed red fox populations may be more prone to infection in areas colonized by D. reticulatus.