Detection of Encephalitozoon cuniculi in the feline cataractous lens.

PURPOSE Identification of Encephalitozoon cuniculi (E. cuniculi) as a possible causative agent for cataracts and uveitis in cats. METHODS Within a 12-month study period, cats that were presented with focal anterior cortical or mature cataract and secondary uveitis underwent a complete ophthalmic examination, complete blood count, serum biochemistry, serologic tests for E. cuniculi and tests for feline immunodeficiency virus (FIV), feline infectious peritonitis (FIP), feline leukemia virus (FeLV) and Toxoplasma gondii (T. gondii). PCR for DNA detection of E. cuniculi and T. gondii as well as cytologic examination of aqueous humor after paracentesis and phacoemulsified lens material were also performed. In addition histopathologic examination of the resected anterior lens capsule and attached lens epithelial cells was performed. Serologic testing for antibodies against E. cuniculi was also performed in 100 ophthalmologically healthy cats. RESULTS Eleven (19 eyes) European shorthair cats with a median age of 3.5 years were included. Nine of 11 cats had bilateral cataracts, with 12/19 eyes having focal anterior cortical cataracts and 7/19 eyes having mature cataracts. In 14/19 eyes anterior uveitis was present. All cats had a positive antibody titer (1:80-1:10,000) for E. cuniculi. Encephalitozoon cuniculi DNA was detected by PCR and sequencing in 18/19 lenses and in 10/19 aqueous samples. Five tentative positive results were detected by cytologic examination. Spores were detected in 15/19 samples of lens material with histopathologic staining. Only 2/100 ophthalmologically healthy cats showed a positive antibody titer for E. cuniculi. CONCLUSION Encephalitozoon cuniculi is a cause of focal anterior cortical cataract and anterior uveitis in cats.