title: Serodiagnosis of paratuberculosis in sheep by use of agar gel immunodiffusion.
abstract: An agar gel immunodiffusion (AGID) test was used over a 3-year period to examine 1,871 serum samples from sheep representing 5 Mycobacterium paratuberculosis-infected flocks and 4 flocks presumed to be uninfected. Of 1,032 sheep, 31 had positive AGID test results (scoring 1 to 5), and 23 of these 31 were necropsied. Infection with M paratuberculosis was confirmed by 1 or more of the following findings: observation of typical lesions on histologic examination of sections of ileum or ileocecal lymph nodes, observation of clumps of acid-fast bacteria in mucosal smears of ileum, and isolation of the organism from feces or tissue. False-positive results on AGID testing were not found in sheep from flocks known to have exposure to Corynebacterium pseudotuberculosis. Diarrhea in infected sheep was observed infrequently; chronic, severe weight loss was the most common sign observed. On histologic examination of tissues from 20 infected sheep, 16 (80%) had diffuse lesions of the ileum and 13 (65%) had acid-fast bacteria in areas of ileal inflammation; 4 had discrete granulomas and peripheral lymphocytic infiltrates in the ileum. Sheep with diffuse lesions tended to have higher mean scores on AGID testing and examination for acid-fast bacteria, compared with those from sheep with more discrete lesions. Bacteriologic culture yielded M paratuberculosis from only 3 sheep with paratuberculosis.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Veterinary Preventive Medicine, College of Veterinary Medicine, Ohio State University, Columbus 43210.
authors.forename: W P
authors.initials: WP
authors.lastname: Shulaw
authors.forename: S
authors.initials: S
authors.lastname: Bech-Nielsen
authors.forename: D M
authors.initials: DM
authors.lastname: Rings
authors.forename: D M
authors.initials: DM
authors.lastname: Getzy
authors.forename: T S
authors.initials: TS
authors.lastname: Woodruff
mesh_terms: D000818:Animals; D005260:Female; D005779:Immunodiffusion / Q000592:standards / Q000662:veterinary*; D008297:Male; D016927:Mycobacterium avium subsp. paratuberculosis / Q000302:isolation & purification; D010283:Paratuberculosis / Q000175:diagnosis* / Q000473:pathology; D012698:Serologic Tests; D012756:Sheep; D012757:Sheep Diseases / Q000175:diagnosis* / Q000473:pathology