Spontaneous Frenkelia infection in a laboratory-reared rat.
Numerous, lobulated, thin-walled protozoan cysts were found in the brain and cervical spinal cord of a male Fischer rat with granulomatous encephalitis. The cysts were compartmented, 470-1000 mum in diameter, and packed with crescent-shaped organisms. Light- and electron-microscopic features of the organism were characteristic of the protozoan Frenkelia, a parasite usually found in the brain of wild rodents. Many cysts were replaced by granulomas, whereas others elicited no inflammation. Perivascular and meningeal mononuclear cell infiltrates and gliosis were common.
D000818:Animals; D016782:Apicomplexa; D001921:Brain / Q000473:pathology; D004660:Encephalitis / Q000473:pathology / Q000662:veterinary*; D005260:Female; D008297:Male; D011528:Protozoan Infections / Q000473:pathology; D011529:Protozoan Infections, Animal; D051381:Rats; D011916:Rats, Inbred F344; D011919:Rats, Inbred Strains; D012376:Rodent Diseases / Q000473:pathology*; D013116:Spinal Cord / Q000473:pathology