The epidemiology of Rickettsia felis infecting fleas of companion animals in eastern Australia

Abstract

Background: Flea-borne spotted fever (FBSF) caused by Rickettsia felis is an arthropod-borne zoonosis. This study aimed to determine the prevalence, primary species and genotype(s) of R. felis infecting fleas from dogs and cats.

Results: All fleas were identified as Ctenocephalides felis felis. All rickettsial DNA detected in fleas was identified as being 100% homologous to R. felis URRWXCal2, with positivity within tropical, subtropical and temperate regions noted at 6.7%, 13.2% and 15.5%, respectively. Toy/small breed dogs were found to be at a lower odds of harboring R. felis-positive fleas compared with large breed dogs on univariate analysis, while DMH and pedigree breed cats were at a lower odds compared to DSH cats. Cooler minimum temperature ranges of between 15 to 20 °C and between 8 to 15 °C increased the odds of R. felis positivity in fleas, as did a constrained maximum temperature range of between 27 to 30 °C on multivariable analysis.

Conclusions: Environmental temperature may play a part in influencing R. felis prevalence and infectivity within its flea host. Regional climatic differences need to be considered when approaching public health risk mitigation strategies for FBSF.

Keywords: Australia; Ctenocephalides felis; Rickettsia; Rickettsia felis; Temperature.

Fig. 1

Collection regions and number of positive animals within each climatic zone

Fig. 2

Distribution of minimum and maximum temperatures amongst positive fleas

Fig. 3

Average daily minimum and maximum environmental temperatures and precipitation for the 7-day period preceding collection of individual fleas