Cat Flea Coinfection with and .

Flea-borne rickettsioses, collectively referred to as a term for etiological agents , , and RFLOs (-like organisms), has become a public health concern around the world, specifically in the United States. Due to a shared arthropod vector (the cat flea) and clinical signs, discriminating between species has proven difficult. While the effects of microbial coinfections in the vector can result in antagonistic or synergistic interrelationships, subsequently altering potential human exposure and disease, the impact of bacterial interactions within flea populations remains poorly defined. In this study, and systems were utilized to assess rickettsial interactions in arthropods. Coinfection of both and within a tick-derived cell line indicated that the two species could infect the same cell, but distinct growth kinetics led to reduced growth over time, regardless of infection order. Sequential flea coinfections revealed the vector could acquire both spp. and sustain coinfection for up to 2 weeks, but rickettsial loads in coinfected fleas and feces were altered during coinfection. Altered rickettsial loads during coinfection suggest and interactions may enhance the transmission potential of either agent. Thus, this study provides a functional foundation to disentangle transmission events propelled by complex interspecies relationships during vector coinfections.