Rickettsia felis: A Review of Transmission Mechanisms of an Emerging Pathogen.

Kelsey Legendre,Kevin Macaluso

doi:10.3390/tropicalmed2040064

Kelsey Legendre, Kevin Macaluso

Open Access

https://doi.org/10.3390/tropicalmed2040064

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Abstract

Rickettsia felis is an emerging pathogen of the transitional group of Rickettsia species and an important cause of febrile illness in Africa. Since the organism’s original discovery in the early 1990s, much research has been directed towards elucidating transmission mechanisms within the primary host and reservoir, the cat flea (Ctenocephalides felis). Several mechanisms for vertical and horizontal transmission within this vector have been thoroughly described, as well as transmission to other arthropod vectors, including other species of fleas. However, while a growing number of human cases of flea-borne spotted fever are being reported throughout the world, a definitive transmission mechanism from arthropod host to vertebrate host resulting in disease has not been found. Several possible mechanisms, including bite of infected arthropods and association with infectious arthropod feces, are currently being investigated.

Highlights

Rickettsia felis is an obligate intracellular bacterium of the transitional group of Rickettsia species, and is the causative agent of emerging flea-borne spotted fever [1]
While much work has been done to investigate the spread of R. felis between cat fleas and to vertebrate hosts, a definitive transmission mechanism that produces a rickettsemic host with clinical signs that mimic the human disease has yet to be found
Rickettsia felis was originally characterized as a typhus-like Rickettsia due to the fact that the first human case was originally misdiagnosed as murine typhus and the organism was initially isolated from a laboratory flea colony

Summary

Introduction

Rickettsia felis is an obligate intracellular bacterium of the transitional group of Rickettsia species, and is the causative agent of emerging flea-borne spotted fever [1]. There have been recent outbreaks of flea-borne rickettsiosis in the United States, including Texas, California, and Hawaii, where data has shown R. felis to be more prevalent in arthropods and mammals via PCR analysis in the area than R. typhi (the etiologic agent of murine typhus) [5,6,7]. Murine typhus is another flea-borne rickettsioses, of the typhus group Rickettsia spp., causing a disease clinically indistinguishable from R. felis. The advent of more sophisticated diagnostic techniques has aided in the distinction of some of these cases [8], allowing for a clearer clinical picture of flea-borne spotted fever

Background

Clinical Disease

Transmission in Arthropods

Transmission to Vertebrates

Findings

Discussion