'Candidatus Mycoplasma haemominutum', a low-virulence epierythrocytic parasite of cats

'Candidatus Mycoplasma haemominutum' is a novel bacterial parasite of domestic cats that causes a low-virulence form of feline infectious anemia. Researchers identified this organism in a cat co-infected with feline leukemia virus and characterized it as distinct from the more pathogenic 'Candidatus Mycoplasma haemofelis'. The organism is approximately 0.3 micrometers in diameter—roughly half the size of related species—and replicates on erythrocyte surfaces. Clinical disease is typically mild or absent, with only minor haematological changes and no fatality associated with infection alone. Tetracycline effectively treats infections within 24 hours. Phylogenetic analysis of 16S rRNA sequences revealed the organism belongs to the family Mycoplasmataceae and is most closely related to Eperythrozoon suis (91% similarity). The organism has not been cultured in vitro and is maintained through in vivo passage in cats. Cats develop IgG antibodies that cross-react partially with antibodies to 'Candidatus Mycoplasma haemofelis', and prior infection provides protection against the more virulent species. The formal Candidatus designation was proposed following established guidelines for uncultivated prokaryotes.

Key findings

• 'Candidatus Mycoplasma haemominutum' is a small (0.3 μm), low-virulence epierythrocytic parasite distinct from the more pathogenic 'Candidatus Mycoplasma haemofelis'
• Phylogenetic analysis reveals the organism belongs to genus Mycoplasma within family Mycoplasmataceae, most closely related to Eperythrozoon suis (91% similarity)
• Clinical disease is typically mild with minor anemia and no mortality; infection is rapidly cleared by tetracycline within 24 hours
• Cats develop protective immunity against more virulent 'Candidatus Mycoplasma haemofelis' following primary infection
• The organism has not been cultured in vitro and must be maintained through in vivo passage in cats