Abstract
The aim of this study was to compare blood copy, haematological and glucose values between cats experimentally infected with either Mycoplasma haemofelis (Group HF: 10 cats), ‘Candidatus M. haemominutum’ (Group HM: 3 cats) or ‘Candidatus M. turicensis’ (Group TU: 3 cats). Blood samples were collected regularly up to 85 days post-infection (DPI) for haemoplasma real-time quantitative PCR, haematology, Coombs’ testing and blood glucose measurement. Statistical analysis was performed using a general linear model (ANOVA) appropriate for a repeated measures experiment with significance set as P<0.05. Cats in Group TU had significantly lower blood copy numbers than cats in Group HF (P<0.001) and HM (P<0.001). All Group HF cats developed anaemia (often severe), macrocytosis and evidence of erythrocyte-bound antibodies whereas Groups HM and TU cats did not. Group HF had significantly lower PCVs, haemoglobin concentrations and red blood cell counts, and significantly higher mean cell volumes, than Groups HM and TU. In Group HF, erythrocyte-bound antibodies reactive at 4°C (both IgM and IgG) appeared between 8 and 22 DPI and persisted for two to four weeks, whereas those reactive at 37°C (primarily IgG) appeared between 22 and 29 DPI and persisted for one to five weeks. In most cats antibodies appeared after the fall in haemoglobin started. Although Group TU had significantly lower glucose concentrations than Groups HF (P=0.006) and HM (P=0.027), mean blood glucose concentrations remained within the reference range in all groups. This study demonstrates that M. haemofelis infection, in contrast to ‘Candidatus M. haemominutum’ and ‘Candidatus M. turicensis’ infection, can result in a severe macrocytic anaemia and the development of cold and warm reactive erythrocyte-bound antibodies.
Highlights
Three feline haemoplasma species are described; Mycoplasma haemofelis,‘Candidatus M. haemominutum’ and ‘Candidatus M. turicensis’(Foley and Pedersen, 2001; Neimark et al, 2001, 2002; Willi et al, 2005; Willi et al, 2006)
Blood was placed into EDTA-anticoagulant for complete blood count using a Cell Dyn 3700 analyser (Abbott, Illinois, USA), packed cell volume (PCV) determination and haemoplasma real-time quantitative PCR, whilst a drop of remaining nonanticoagulated blood was used for blood glucose measurement (Accu-chek Aviva blood glucose system, Roche Diagnostics Ltd., Lewes, East Sussex, UK)
The inoculum dose used for Group TU was far lower than for Group HF, it was only about half that used for Group HM, yet the maximal copy numbers reached in Groups TU and HM differed by several logs
Summary
Three feline haemoplasma species are described; Mycoplasma haemofelis,‘Candidatus M. haemominutum’ and ‘Candidatus M. turicensis’(Foley and Pedersen, 2001; Neimark et al, 2001, 2002; Willi et al, 2005; Willi et al, 2006). Three feline haemoplasma species are described; Mycoplasma haemofelis,. M. haemofelis infection often causes haemolysis (Berent et al, 1998; Foley et al, 1998; Westfall et al, 2001) but ‘Candidatus M. haemominutum’ infection does not usually result in clinically significant anaemia (Foley et al, 1998; Westfall et al, 2001; Tasker et al., 2006a) without concurrent immunocompromisation (George et al, 2002). Experimental ‘Candidatus M. turicensis’ has only been evaluated in one previous study in which two cats developed anaemia secondary to infection (Willi et al, 2005). Positive Coombs’ (direct antiglobulin) tests, indicating the presence of erythrocyte-bound antibodies, have been reported with haemoplasma infections in a number of species, including cats (Bundza et al, 1976; Harvey and Gaskin, 1978; Hoffmann et al, 1981).
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