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Clinical Aspects of Veterinary Listeriosis
Dr. David Larson, DVM, MSIowa State Veterinary Diagnostic Laboratory
Dr. Arach Wilson, DVM, MSUSDA-APHIS-VS, National Center for Animal Health, Pathobiology Laboratory, Special Pathology Services
Irene V. Wesley, DrPHUSDA-ARS-National Animal Disease Center
ListeriaListeria monocytogenesmonocytogenes• All livestock species
• Cattle, sheep, goats
• Three clinical manifestations
Encephalitis
Abortion
Septicemia
Listeriosis cases 2000-2007 ISU Veterinary Diagnostic Lab
0
20
4060
80
100
120
140
Bovine Ovine Camelid Caprine
AbortionBacterial IsoEncephalitisSepticemia
Num
ber o
f Cas
es
Courtesy of Randy Berghefer, ISU
Seasonal Distribution
Wesley et al. 2002. J Vet Diagn Invest.14: 314-321
Diagnostic flow chart
Wesley et al. 2002. Microbial Food Safety In Animal Agriculture pp.233-241
Encephalitis: Clinical Symptoms
• Depressed/disoriented• Head pressing• Circling• Ataxia• Head tilt• Facial paralysis• Facial hypoalgesia• Paresis of jaw muscles
Copyright NADIS 2004
Differential Diagnosis
ListeriosisRabiesThromboembolic meningoencephalitis(TEME) PolioencephalomalaciaTransmissible Spongiform Encephalopathies(TSE)etc.
Methods ComparisonBact Isol Gram (+) IHC (+)
YES 17/25 17 9/17 16/17
NO 8/25 8 3/8 5/8
NO ATTEMPT
13/38 13 6/13 10/13
TOTAL 17/25(68%)
13/38 (34.2%)
31/38 (81.5%)
Johnson et al. 1995. J Vet Diagn Invest 7:223-228
Immunohistochemistry (IHC)Listeria in brain micro-abscess
Johnson et al. 1995. J Vet Diagn Invest 7:223-228
Gram stain of ovine brainstem
Johnson et al. 1995. J Vet Diagn Invest 7:223-228
IHC of Listeria in bovine brainstem
Loeb 2004. J. Vet Med 51: 453-455.
Case Histories
• Clinically healthy carriers!
• Bovine• Sheep• Alpaca
Encephalitis
• No gross lesions in brain• Perviascular cuffing of vessels in brain stem• Microabscesses in the neuropil• Leptomeningitis may be present• Ocular iritis and keratoconjunctivitis RARE
IHC of Listeria in ovine brainstem
Wesley et al. 2002. J. Vet Diagn Invest. 14: 314-321
Septicemia (generalized listeriosis)
Most common in neonatesFeverDepressionEmaciationDiarrheaNystagmusOpisthotonos
Courtesy of Deb Hoyt, ISU
Abortion
•Sporadic or up to 15% of herd
•Usually in last trimester without clinical signs (~280 day gestation-bovine)
•Fetus dies in utero, stillbirths, neonatal deaths
•Dystocia, retained placenta
Conclusion
• Progress since 1926!• Molecular methods complement
diagnostic assays
Acknowledgements
James Fosse, Visual ServicesRandy Berghefer, Computer
SpecialistDeb Hoyt, Medical Technologist
Dr. Amir Hamir, Pathologist
