A growing number of recent reports have implicated Rickettsia felis as a human pathogen, paralleling the increasing detection of R. felis in arthropod hosts across the globe, primarily in fleas. Here Anopheles gambiae mosquitoes, the primary malarial vectors in subSaharan Africa, were fed with either blood meal infected with R. felis or infected cellular media administered in membrane feeding systems. In addition, a group of mosquitoes was fed on R. felisinfected BALB/c mice. The acquisition and persistence of R. felis in mosquitoes was demonstrated by quantitative PCR detection of the bacteria up to day 15 postinfection. R. felis was detected in mosquito feces up to day 14. Furthermore, R. felis was visualized by immunofluorescence in salivary glands, in and around the gut, and in the ovaries, although no vertical transmission was observed. R. felis was also found in the cotton used for sucrose feeding after the mosquitoes were fed infected blood. Natural bites from R. felisinfected An. gambiae were able to cause transient rickettsemias in mice, indicating that this mosquito species has the potential to be a vector of R. felis infection. This is particularly important given the recent report of high prevalence of R. felis infection in patients with "fever of unknown origin" in malaria-endemic areas.Rickettsia felis | spotted fever | Anopheles gambiae I n 2002, Rickettsia felis, an obligate intracellular bacterium that belongs to the spotted fever group of Rickettsia, was definitively described (1, 2). Over the past 2 decades, an increasing number of reports have implicated R. felis as a human pathogen, paralleling an increase in reports of the detection of R. felis in arthropod hosts throughout the world (1, 3).By 2011, more than 70 human cases of R. felis had been reported worldwide, including in Central and South America, Asia, northern Africa, and Europe (1). More cases have been published since then, including the first probable human cases in Australia (4). In sub-Saharan Africa, recent studies have challenged the importance of R. felis infection in patients with "fever of unknown origin," with this bacterium detected in up to 15% of such patients (5-7). In 2011, a potential R. felis primary infection, called "yaaf," was suspected in the case of an 8-mo-old girl in Senegal with polymorphous skin lesions similar to those seen in patients from Mexico (8). The epidemiologic and clinical picture of this emerging infection in Africa, including its potential vectors, is poorly understood, however.Various arthropods, but primarily fleas, have been associated with R. felis (1, 3). More specifically, the cat flea Ctenocephalides felis is the arthropod in which R. felis has been most frequently detected. To date, it is the sole confirmed biological vector of R. felis, with both horizontal and vertical transmission making this flea a potential reservoir for this bacterium (9-11). However, in some countries where R. felis appears to be highly prevalent, such as Senegal, neither cat fleas nor other arthropods have been...