Encephalitozoon cuniculi strain III is a cause of encephalitozoonosis in both humans and dogs

Microsporidia are obligate intracellular eukaryotic organisms found in a wi de range of vertebrate and invertebrate hosts. Encephalitozoon cuniculi is commonly found in domestic rabbits and rodents and also occurs in dogs, oth er canids, and primates, including humans. DNA sequencing of the ribosomal RNA genes has been used to identify these parasites to a species level and to define E. cuniculi strains I, II, and III. Eight new dog isolates were c haracterized as E. cuniculi strain III by use of molecular methods, This st rain has also been identified in isolates from immunocompromised humans, su ggesting the zoonotic potential of this parasite species. Prolonged microsp oridial spore shedding from asymptomatic dogs is also reported.