Vector-Borne Disease Laboratories, Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, United States of America.
Department of Microbiology and Immunology, College of Medicine, University of South Alabama, Mobile, Alabama, United States of America.
PLoS Negl Trop Dis. 2022 Jun 27;16(6):e0010576. doi: 10.1371/journal.pntd.0010576. eCollection 2022 Jun.
Rickettsia felis is an emerging etiological agent of rickettsioses worldwide. The cosmopolitan cat flea (Ctenocephalides felis) is the primary vector of R. felis, but R. felis has also been reported in other species of hematophagous arthropods including ticks and mosquitoes. Canines can serve as a bacteremic host to infect fleas under laboratory conditions, yet isolation of R. felis from the blood of a vertebrate host in nature has not been realized. Cofeeding transmission is an efficient mechanism for transmitting rickettsiae between infected and uninfected fleas; however, the mechanism of transmission among different orders and classes of arthropods is not known. The potential for R. felis transmission between infected fleas and tick (Dermacentor variabilis) and mosquito (Anopheles quadrimaculatus) hosts was examined via cofeeding bioassays. Donor cat fleas infected with R. felis transmitted the agent to naïve D. variabilis nymphs via cofeeding on a rat host. Subsequent transstadial transmission of R. felis from the engorged nymphs to the adult ticks was observed with reduced prevalence in adult ticks. Using an artificial host system, An. quadrimaculatus exposed to a R. felis-infected blood meal acquired rickettsiae and maintained infection over 12 days post-exposure (dpe). Similar to ticks, mosquitoes were able to acquire R. felis while cofeeding with infected cat fleas on rats infection persisting in the mosquito for up to 3 dpe. The results indicate R. felis-infected cat fleas can transmit rickettsiae to both ticks and mosquitoes via cofeeding on a vertebrate host, thus providing a potential avenue for the diversity of R. felis-infected arthropods in nature.
全世界范围内，猫栉首蚤（Ctenocephalides felis）是导致立克次体病的主要原因。猫栉首蚤是猫栉首蚤的主要媒介，但也有报道称，其他吸血节肢动物，包括蜱虫和蚊子中也存在猫栉首蚤。在实验室条件下，犬类可以作为菌血症宿主，感染跳蚤，但尚未在自然环境中的脊椎动物宿主血液中分离到猫栉首蚤。共同喂养传播是感染和未感染跳蚤之间传播立克次体的有效机制；然而，不同目和纲的节肢动物之间的传播机制尚不清楚。通过共同喂养生物测定法，研究了感染跳蚤与蜱虫（Dermacentor variabilis）和蚊子（Anopheles quadrimaculatus）宿主之间猫栉首蚤传播的可能性。通过共同喂养大鼠宿主，感染猫栉首蚤的供体跳蚤将病原体传播给未感染的 D. variabilis 若虫。随后观察到从饱食的若虫到成年蜱虫的跨龄传播，成虫蜱虫中的感染率降低。使用人工宿主系统，暴露于感染了猫栉首蚤的血液中的 An. quadrimaculatus 获得了立克次体，并在暴露后 12 天（dpe）仍保持感染。与蜱虫类似，蚊子在与感染猫栉首蚤共同喂养大鼠时也能获得猫栉首蚤，感染可在蚊子中持续 3 dpe。结果表明，感染了猫栉首蚤的跳蚤可通过共同喂养脊椎动物宿主将立克次体传播给蜱虫和蚊子，从而为自然界中感染了立克次体的节肢动物的多样性提供了一种潜在途径。
