|Larson, D - IOWA STATE UNIVERSITY|
|Harmon, K - IOWA STATE UNIVERSITY|
|Schwartz Ramos, A - FOOD SAFETY NET SERVICES|
Submitted to: Journal of Veterinary Diagnostic Investigation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 3, 2001
Publication Date: July 20, 2002
Citation: WESLEY, I.V., LARSON, D., HARMON, K., LUCHANSKY, J.B., SCHWARTZ RAMOS, A. A CASE REPORT OF SPORADIC OVINE LISTERIAL MENIGOENCEPHALITIS IN IOWA WITH AN OVERVIEW OF LIVESTOCK AND HUMAN CASES. JOURNAL OF VETERINARY DIAGNOSTIC INVESTIGATION. 2002. V. 14. P. 314-321. Interpretive Summary: Listeria monocytogenes is a major human foodborne pathogen. At least one outbreak involved consumption of coleslaw obtained from a farm where manure from sheep with past histories of listeriosis was used. The goal of this project was to determine if cases of listerosis in sheep could have human public health consequences. We studied a case of sheep listeriosis, on a premise where soybean sprouts were raised for the organic health food market. After the death of two lambs on the premises, we isolated L. monocytogenes from healthy sheep, well water, and soybean cleanings. We showed that the DNA profile of L. monocytogenes recovered from the lamb's brain was distinctly different from isolates from feces of clinically healthy sheep. We also demonstrated that the DNA pattern of L. monocytogenes from clinically healthy sheep and soybean cleanings, in some cases, matched, which suggests this as possible source of contamination. This emphasizes the potential impact of transmitting diseases from livestock to human foods. The methods used in this study have practical application to USDA action agencies, including APHIS and FSIS.
Technical Abstract: To determine the source of L. monocytogenes in a flock of sheep. The index case was a male lamb, which was part of a flock of 85 sheep located in central Iowa. The sheep were raised on a premise where soybean sprouts were also cultivated for the organic foods market. Clinical and environmental samples were cultured for L. monocytogenes. Isolates were serotyped and analyzed using pulsed field gel electrophoresis (PFGE). Listeria monocytogenes (serotype 1) was recovered from the brain of a male lamb with clinical signs of listerial encephalitis. Isolates of serotypes 1 and 4 were also cultured from feces of clinically healthy lambs, compost piles, and soybean cleanings. By pulsed field gel electrophoresis (PFGE) the clinical isolate was distinctly different from the other isolates. Field isolates were identified as L. monocytogenes serotypes 1and 4. However, by PFGE none matched the profile exhibited by the clinical isolate. Thus, the ultimate source of contamination is unknown. This represented a sporadic incident of ovine listerial encephalitis. Because the lamb was raised on a premise on which vegetables for human consumption were cultivated, major public health concerns emerged.