Also Known As: Pasture Fever — Tickborne Fever — Ruminant Anaplasmosis — TBF
Caused By: Anaplasma phagocytophilum, previously known as Ehrlichia phagocytophila
Seasonal pasture fever occurs in cattle that are returned to tick infected pasture in the Spring.
Human granulocytic ehrlichiosis, the zoonotic form of TBF is a potentially fatal disease reported in the UK, Europe and USA.
TBF naturally affects primarily sheep and cattle, and less commonly, deer, horses and dogs.
TBF causes multisystemic disease, causing cardiovascular, gastrointestinal, respiratory, reproductive and neurological signs, and also lymphadenopathy and wasting disease.
Severe haematological changes including profound anaemia and leucopaenia cause significant clinical signs.
Recovered animals develop immunity but it is unknown how long this is effective for.
Haematological and Biochemical changes as listed above along with marked pyrexia are highly suggestive, especially if historical findings are conducive.
Demonstration of the organism in the leucocytes in peripheral blood is confirmative.
On post-mortem examination, the spleen is enlarged and mild liver damage is common. Lesions within the lung are present and contain mononuclear infiltrate on histopathology. Thickening, ulceration and haemorrhage of the gastrointestinal tract become worse distally.
The parasites may be visible within the neutrophils in sections of liver and lung.
A. phagocytophilum is susceptible to oxytetracycline, sulphamethazine, sulphadimidine, doxycycline and trimethoprim-sulphonamides.
Human Granulocytic Ehrlichiosis
Causes fever, malaise, headaches, sweats, nausea, confusion, anorexia, vomiting, weakness, diarrhoea, pneumonia, vertigo, seizures, GI bleeding and a skin rash.
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- Miert, A. S. J. P. A. Mvan., Duin, C. T. Mvan., Schotman, A. J. H., Franssen, F. F. (1984) Clinical, haematological and blood biochemical changes in goats after experimental infection with tick-borne fever. Vet Parasitology, 16(3/4):225-233; 29
- Bakken, J. S., Krueth, J., Tilden, R. L., Dumler, J. S., Kristiansen, B. E. (1996). Serological evidence of human granulocytic ehrlichiosis in Norway. Eur J Clin Microbiol Inf Dis, 15(10):829-832; 12
The datasheet was accessed on 6 June 2011.
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