Prevalence and risk factors for Mycoplasma spp. positivity in cat blood donor units from Portugal, Spain and Belgium in 2022: retrospective study on 7573 blood donations from 4121 healthy donor cats

Haemotropic mycoplasmas are epi-erythrocytic parasitic bacteria that can cause haemolytic anaemia. Prevalence for haemoplasma infection varies geographically among Mycoplasma species. Male adult outdoor non-pedigree cats are at increased risk for infection. Some studies identified an association between haemoplasmas and retroviruses. As Mycoplasma spp. can be transmitted via blood transfusion, routine quantitative polymerase chain reaction (qPCR) screening of donor cats is recommended. This retrospective study assessed prevalence and risk factors for Mycoplasma spp. positivity in cat donor units from Portugal, Spain, and Belgium. A private blood bank database of cat donations performed in 2022 was reviewed. Studied risk factors for Mycoplasma spp. positivity included age, sex, pedigree, blood type, geographic area, season, and retroviral co-infection (FeLV and FIV). A multiple generalised estimation equation model was used to account for repeated blood donations on a same cat. A total of 7573 blood donations from 4121 privately-owned mixed breed donor cats from Portugal (n=4034, 97.9%), Spain (n=70, 1.7%), and Belgium (n=17, 0.4%) were studied. Most cats donated blood once (n=1996, 48.4%); the remainder donated twice (n=1099, 26.7%), three (n=725, 17.6%) or four (n=301, 7.3%) times. Two-hundred and twelve Portuguese cats tested positive at least once for Mycoplasma spp. leading to an estimated prevalence of 5.3% (95% CI: 4.6-5.9). The prevalence did not significantly differ between Portuguese regions (P=0.28). Two cats in Spain had positive Mycoplasma spp. qPCR, whilst all Belgian cats were negative. The small sample sizes in these countries prevented robust prevalence estimation. Among positive Portuguese cats, 30 cats donated blood >1 time in 2022: 26 cats were negative first then subsequently tested positive, 3 cats were positive on two occasions, and 1 cat was initially positive and subsequently tested negative. Blood units collected from male cats were at higher risk for Mycoplasma spp. positivity (OR 1.9, P<0.001). Increased risk was also observed for blood units that tested positive for FeLV either by serology and/or qPCR (OR 2.9, P=0.0018) and for blood donations performed in winter (OR 2.5, P<0.0001). None of the other studied risk factors was associated with Mycoplasma spp. positivity. European cat blood donors displayed a low prevalence of Mycoplasma spp. with an increased risk in cats affected with FeLV and male cats. The seasonality for Mycoplasma spp. positivity, with an increased risk in winter, remains to be elucidated. Positive Mycoplasma spp. qPCR results identified in previously negative donors emphasizes the importance of testing on every donation instead of annually.