Abstract
Three groups of 9 months old lambs, each group consisting of 5 animals, were infected experimentally with Eperythrozoon ovis (Eo), Listeria monocytogenes (Lm) and Eo/Lm, respectively. The animals infected with Eo developed haemolytic anaemia, but otherwise no clinical symptoms were seen. The animals infected with Lm had a period with fever and reduced appetite after infection. These symptoms lasted longer and were more pronounced in the group with the dual infection (Eo/Lm). None of the lambs developed clinical meningo-encephalitis during the experiment.
Group Lm developed the highest reciprocal geometrical mean titres against Lm. No titer rise was found in group Eo, while group Eo/Lm had a slight rise towards the end of the experiment. Group Eo/Lm also had the strongest delayed hypersensitivity reaction against Lm.
After Eo infection, a fall in packed cell volume, haemoglobin, number of red cells, and plasma glucose and an increase in serum iron were recorded. Serum iron dropped and serum copper increased after infection with Lm.
In this experiment the blood changes induced by Eo, i.e. haemolytic anaemia and acidosis, led to a prolonged state of illness in animals infected with Lm, in addition to inhibited development of antibody titres, but not to clinical meningoencephalitis.
Keywords: sheep, Eperythrozoon ovis, Listeria monocytogenes, immunity, haemolytic anaemia, acidosis
Sammendrag
Tre grupper med 9 mnader garnie lam, kvar gruppe p 9 dyr, blei brukte i forsøket. Dei blei infiserte med Eperythrozoon ovis (Eo), Listeria monocytogenes (Lm) og Eo/Lm. Dyr infiserte med Eo fekk hemolytisk anemi, men viste elles ikkje teikn pà sjukdom. Dyr infiserte med Lm fekk ein periode med feber og nedsatt matlyst, og desse symptoma var sterkast og varde lengst i gruppa med kombinert infeksjon (Eo/Lm). Ingen av dyra synte teikn p meningo-encephalitt. Gruppe Lm utvikla dei høgaste geometriske gjennomsnittstitra mot Lm. Inga titerstiging blei funnen i gruppe Eo, mens gruppc Eo/Lm hadde ei svak titerstiging mot slutten av eksperimentet. Gruppe Eo/Lm hadde sterkast seinka hypersensitivitetsreaksjon.
Dyr infiserte med Eo hadde eit sterkt fall i hematokrit (PCV) og plasma glukose og ein auke i serum jern, serum jern fall euer infeksjon med Lm.
I dette eksperimentet førte blodendringane ved ein Eo-infeksjon (hemolytisk anemi og acidose) til ein alvorleg sjukdomstilstand hos dyr som var infiserte med Lm. Dei førte vidare til ei hemma utvikling av antistofftiter, men ikkje til symptom p meningo-encephalitt.
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Footnotes
This work was supported by grants from the Norwegian Agricultural Research Council.
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