Abstract
The haematological effects of heavy tick infestation were investigated in eight koalas. In six koalas with uncomplicated tick infestation erythroid regeneration was characterised by enhanced reticulocytosis, increased numbers of circulating nucleated erythroid cells (CNEC) and the occurrence of erythrocyte granular inclusions (EGI). EGI were determined from transmission electron microscopy to be primarily mitochondria with ferruginous micelles between cristae. Recovery from anaemia took 3–5 weeks. Leucocyte changes on recovery were restricted to increased lymphocytes for five and increased eosinophils for four of the six koalas. In the two koalas with underlying disease and tick infestation the anaemia was still characterised by increased levels of CNEC and the presence of EGI but enhanced reticulocytosis was absent or limited. These results suggest that enhanced reticulocytosis is a good indicator of regenerative anaemia in the koala. Enhanced CNEC and EGI may accompany the regenerative response but their presence alone may not be sufficient to indicate regeneration.
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Spencer, A.J., Canfield, P.J. Haematological characterisation of heavy tick infestation in koalas (Phascolarctos cinereus). Comparative Haematology International 3, 225–229 (1993). https://doi.org/10.1007/BF02341970
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DOI: https://doi.org/10.1007/BF02341970