Data from: Co-feeding intra- and interspecific transmission of an emerging insect-borne rickettsial pathogen

Cat fleas (Ctenocephalides felis) are known as the primary vector and reservoir of Rickettsia felis, the causative agent of flea-borne spotted fever; however, field surveys regularly report molecular detection of this infectious agent from other blood-feeding arthropods. The presence of R. felis in additional arthropods may be the result of chance consumption of an infectious bloodmeal, but isolation of viable rickettsiae circulating in the blood of suspected vertebrate reservoirs has not been demonstrated. Successful transmission of pathogens between actively blood-feeding arthropods in the absence of a disseminated vertebrate infection has been verified, referred to as cofeeding transmission. Therefore, the principal route from systemically infected vertebrates to uninfected arthropods may not be applicable to the R. felis transmission cycle. Here, we show both intra- and interspecific transmission of R. felis between cofeeding arthropods on a vertebrate host. Analyses revealed that infected cat fleas transmitted R. felis to naïve cat fleas and rat fleas (Xenopsylla cheopis) via fleabite on a nonrickettsemic vertebrate host. Also, cat fleas infected by cofeeding were infectious to newly emerged uninfected cat fleas in an artificial system. Furthermore, we utilized a stochastic model to demonstrate that cofeeding is sufficient to explain the enzootic spread of R. felis amongst populations of the biological vector. Our results implicate cat fleas in the spread of R. felis amongst different vectors, and the demonstration of cofeeding transmission of R. felis through a vertebrate host represents a novel transmission paradigm for insect-borne Rickettsia and furthers our understanding of this emerging rickettsiosis.猫蚤（Ctenocephalides felis）是菲氏立克次体（Rickettsia felis）的主要传播媒介与储存宿主，该病原体为蚤传斑点热的致病原；但野外调查常可从其他吸血节肢动物中分子检测到该传染性病原体。除猫蚤外，其他节肢动物中检出菲氏立克次体的现象，可能源于偶然吸食了感染性血餐，但目前尚未证实可从疑似脊椎动物储存宿主的血液中分离到存活的立克次体。在未发生全身性脊椎动物感染的情况下，活跃吸血的节肢动物之间成功实现病原体传播的现象已被证实，该过程被称为共食传播。因此，“全身性感染脊椎动物向未感染节肢动物传播病原体”这一经典传播途径，或许并不适用于菲氏立克次体的传播循环。本研究证实了在脊椎动物宿主体表共栖的节肢动物之间，菲氏立克次体可发生种内与种间传播。分析结果显示，感染了菲氏立克次体的猫蚤可在非立克次体血症的脊椎动物宿主上，通过叮咬将病原体传播给未感染的易感猫蚤及印鼠客蚤（Xenopsylla cheopis）。此外，在人工系统中，经共食感染的猫蚤可将病原体传染给新羽化的未感染易感猫蚤。本研究还利用随机模型证实，共食传播足以解释菲氏立克次体在生物媒介种群中的地方性流行扩散。本研究结果表明，猫蚤可介导菲氏立克次体在不同媒介种群间扩散；而经脊椎动物宿主实现菲氏立克次体共食传播的证实，为虫媒立克次体构建了全新的传播范式，也进一步加深了我们对这一新发立克次体病的认知。