The Ctenocephalides felis-associated pathogens Bartonella spp., Rickettsia felis, Mycoplasma haemofelis (Mhf), 'Candidatus M. haemominutum' (Mhm), and 'Candidatus M. turicensis' (CMt) are common in cats and fleas around the world. R. felis is the cause of flea-borne spotted fever, an emerging infectious disease of humans. The objective of this study was to define the prevalence of these organisms in cats and fleas in Sydney, Melbourne and Brisbane, Australia.

Veterinarians in participating clinics collected blood (EDTA), serum, and fleas (at least 2 fleas per cat) from 111 cats with C. felis infestations. The samples were stored at -20°C until shipped to Colorado State University. DNA was extracted from the blood and fleas for performance of previously reported conventional PCR assays that amplify the DNA of Bartonella spp., Mhf, Mhm, CMt, and Rickettsia spp.. Band size was used to determine Bartonella spp. Samples giving a band appropriate for Mhf or CMt in the hemoplasma PCR assay and all Rickettsia spp. positive samples with adequate DNA were sequenced. Sera were assayed for Bartonella spp. IgG by ELISA.

From the 111 cats, DNA of Mhf, CMt, and Mhm was amplified from one cat (0.9%), one cat (0.9%), and 17 cats (15.3%), respectively. Of the 111 flea sets, DNA of Mhm (62 sets; 55.9%) but not Mhm or CMt was amplified. Bartonella spp. IgG was detected in 42 cats (37.8%), 11 of these cats (26.2%) were positive for Bartonella spp. DNA in blood. Overall, the prevalence rates for Bartonella spp. DNA in the cats and the flea sets was 15.3% (17 cats) and 28.8% (32 flea sets), respectively. Some cats and flea sets were infected with B. henselae alone, B. clarridgeiae alone, or both B. henselae and B. clarridgeiae. Rickettsia felis DNA was amplified from 22 of the flea sets (19.8%), but none of the cat blood samples. Overall, DNA of one or more of the organisms was amplified from 27% (30 of 111) of the cats and 67.6% (75 of 111) of the flea sets.

This is the first study to determine R. felis prevalence rates in C. felis and the cats from which they were collected in Australia. Results of this study document that C. felis-associated infectious agents are common in cats and fleas in Eastern Australia and support the recommendation that stringent flea control be maintained on cats.