The association of host and vector characteristics with pathogen and endosymbiont infection.

Surveillance of the fleas and flea-borne pathogens infecting cats is important for both human and animal health. Multiple zoonotic and species are known to infect the most common flea infesting cats and dogs worldwide: , the cat flea. The ability of other flea species to transmit pathogens is relatively unexplored. We aimed to determine cat host and flea factors independently associated with flea and infection. We also assessed flea and cat infection by flea-host pair and location. To accomplish these aims, we performed qPCR for the detection of , hemotropic , , and DNA using paired cat and flea samples obtained from free-roaming cats presenting for spay or neuter across four locations in the United States. A logistic regression model was employed to identify the effect of cat (sex, body weight, geographic location, and , hemotropic , and spp., infection) and flea (clade and and infection) factors on . infection. From 189 free roaming cats, we collected 84 fleas: (78/84), (4/84), (1/84), and (1/84). were phylogenetically assigned to Clades 1, 4, and 6 by gene amplification. (52/84) and . (16/84) were the most common pathogenic bacteria detected in fleas. Our model identified host cat sex and weight as independently associated with . infection in fleas. (52/84), (7/84) and (7/84) were detected in specific clades: . was detected only in Clades 1 and 6 while . and . were detected only in Clade 4. spp., also displayed clade specificity with strains other than wCfeT only infecting fleas from Clade 6. There was poor flea and host agreement for spp., infection; however, there was agreement in the species detected in cats and fleas by geographic location. These findings reinforce the importance of considering reservoir host attributes and vector phylogenetic diversity in epidemiological studies of flea-borne pathogens. Widespread sampling is necessary to identify the factors driving flea-borne pathogen presence and transmission.