Chlamydia felis: Lack of association between clinical signs and the presence of the cryptic plasmid

Chlamydia felis is an obligate intracellular bacterial pathogen that infects cats, causing severe conjunctivitis associated with upper respiratory tract disease (URTD). In the present study, 186 cats from three non-commercial catteries in São Paulo, SP, Brazil were evaluated. The detection of Chlamydia felis was performed by PCR. The clinical severity was scored from 1 to 4, with a score of 4 as the most severe manifestation. The total occurrence of C. felis was of 18.82% (35/186) of cats overall, but notably, 58.06% (18/31) of infected cats originated from a single cattery. All animals harboring C. felis had URTD clinical signs and higher scores (3 and 4). In addition, C. felis occurrence was associated with the presence of cryptic plasmid. However, the virulence and clinical severity were not correlated.