Baylisascaris transfuga (Ascaridoidea, Nematoda) from European brown bear (Ursus arctos) causing larva migrans in laboratory mice with clinical manifestation.

Due to the recent recovery of brown bear populations in Central Europe, information about their ascarid parasite, Baylisascaris transfuga is necessary as the parasite represents a part of natural ecological networks. B. transfuga can lead to larva migrans syndrome in accidental hosts, but its zoonotic potential has not been confirmed. The resent study compares development of larva migrans in infected mice inoculated with two infectious doses (ID 200 and ID 2000) of B. transfuga embryonated eggs, and the clinical manifestation to evaluate the pathogenicity of the larvae. Histopathology revealed that the liver was the most severely infected organ. The moderately infected organs included lung, brain, skeletal muscles and jejunum and the less infected ones were the eyes, heart, kidneys and spleen. The high pathogenicity of B. transfuga to mice was reflected in high mortality (33,3%) after infection, with mortality increasing with higher infectious dose. The results extend the knowledge of the interaction of B. transfuga and its aberrant hosts and contribute to the understanding of the epidemiology and transmission of this bears roundworm.