Listeriosis in sheep: Tick-borne fever used as a model to study predisposing factors [Listeria monocytogenes, Ehrlichia phagocytophila, immunity, blood components, bone marrow, cerebrospinal fluid]

• Published in: Acta veterinaria scandinavica 1980-01, Vol.21 (4), p.533-545
• Main Authors: Groenstoel, H, Oeveraas, J. (State Veterinary Research Station for Small Ruminants, Sandnes (Norway))
• Format: Article
• Language: English
• Subjects: Animals; Disease Models, Animal; Encephalitis, Tick-Borne - complications; Encephalitis, Tick-Borne - veterinary; Listeriosis - etiology; Listeriosis - veterinary; Meningitis, Listeria - etiology; Meningitis, Listeria - veterinary; Sheep; Sheep Diseases - etiology
• ISSN: 0044-605X; 1751-0147; 1751-0147
• DOI: 10.1186/BF03546841

Three groups of 6 months old lambs, each group consisting of 5 animals, were infected experimentally with Ehrlichia phagocytophila (Ep), Listeria monocytogenes (Lm) and Ep/Lm, respectively. All the animals had a period with fever and reduced appetite after infection, and these symptoms were most pronounced in the group with the combined infection (Ep/Lm). One animal in group Lm developed listeric meninigo-encephalitis. Lm was isolated from blood samples from both groups infected with Lm during the first week after infection, and from faecal samples during the first 2 weeks. Lm was also isolated from organs from several animals in these 2 groups at post-mortem examination. Group Ep/Lm developed the highest reciprocal geometrical mean titres and the stromgest delayed hypersensitivity reaction against Lm. After infection, a fall in serum iron and albumin was recorded, and the groups infected with Ep had a substantial fall in neutrophils. The myeloid : erythroid ratio in the bone marrow tended to decrease in Group Ep/Lm after infection. An increase in leucocyte counts and total protein content was found in the cerebrospinal fluid in the 2 groups infected with Lm, The experiment indicates that the blood changes induced by tick-borne fever viz, neutropenia and probably also impaired function of the neutrophils, may predispose for listeric septicaemia, but probably not for listeric meningo-encephalitis.