Prevalence and infection load dynamics of Rickettsia felis in actively feeding cat fleas.
BACKGROUND
Rickettsia felis is a flea-associated rickettsial pathogen recurrently identified in both colonized and wild-caught cat fleas, Ctenocephalides felis. We hypothesized that within colonized fleas, the intimate relationship between R. felis and C. felis allows for the coordination of rickettsial replication and metabolically active periods during flea bloodmeal acquisition and oogenesis.


RESULTS
A quantitative real-time PCR assay was developed to quantify R. felis in actively feeding R. felis-infected fleas. In three separate trials, fleas were allowed to feed on cats, and a mean of 3.9x10(6) R. felis 17-kDa gene copies was detected for each flea. A distinct R. felis infection pattern was not observed in fleas during nine consecutive days of bloodfeeding. However, an inverse correlation between the prevalence of R. felis-infection, which ranged from 96% in Trial 1 to 35% in Trial 3, and the R. felis-infection load in individual fleas was identified. Expression of R. felis-infection load as a ratio of R. felis/C. felis genes confirmed that fleas in Trial 3 had significantly greater rickettsial loads than those in Trial 1.


CONCLUSIONS
Examining rickettsial infection dynamics in the flea vector will further elucidate the intimate relationship between R. felis and C. felis, and facilitate a more accurate understanding of the ecology and epidemiology of R. felis transmission in nature.
Reif
Kathryn E
KE
Department of Pathobiological Sciences, Louisiana State University, Baton Rouge, Louisiana, United States of America.
Stout
Rhett W
RW
Henry
Gretchen C
GC
Foil
Lane D
LD
Macaluso
Kevin R
KR
D000818:Animals; D018407:Bacterial Physiological Phenomena; D002415:Cats; D004463:Ecology; D005260:Female; D007700:Kinetics; D008297:Male; D008954:Models, Biological; D010957:Plasmids / Q000378:metabolism; D012337:RNA, Ribosomal, 18S / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012282:Rickettsia Infections / Q000453:epidemiology* / Q000382:microbiology*; D041161:Rickettsia felis / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D005423:Siphonaptera / Q000382:microbiology*; D013997:Time Factors
D012337:RNA, Ribosomal, 18S