Lethal Encephalitozoon cuniculi genotype III infection in Steppe lemmings (Lagurus lagurus)

- We report a lethal infection in lemmings caused by Encephalitozoon cuniculi genotype III.
- Molecular and histological methods were used for evaluation.
- E. cuniculi infection was found in all organs including brain.
- Pet rodents could represent a potential source of the E. cuniculi for humans.

Microsporidia are ubiquitous, spore-forming, intracellular parasites infecting invertebrates and vertebrates. Some of them are important opportunistic pathogens in humans, including three species of genus Encephalitozoon. Intraspecies genetic variation with a different range of hosts is known in Encephalitozoon cuniculi distinguishing four genotypes. Recently, E. cuniculi is often observed in pet animals, mainly E. cuniculi genotype I in pet rabbits. This study described a fatal encephalitozoonosis in a group of pet rodents Steppe lemmings (Lagurus lagurus). The animals were presented with progressive weight loss, aggression, cannibalism, purulent conjunctivitis and hind limb paresis. Death occurred within 48 h after the onset of clinical signs. The group comprised of 15 animals was affected and died within a period of three months. Post-mortal examination did not show any macroscopic changes. Microsporidial vacuoles with typical spores were found in brain and kidney tissues and E. cuniculi DNA in all tested organs. The internal transcribed spacer region (ITS) of rRNA gene showed 100% homology with E. cuniculi genotype III previously identified in dogs, tamarin colonies from zoos, swine, birds and humans. Pet lemmings could represent a new potential source of the infection for their breeders.