Testing the Competence of Cimex lectularius Bed Bugs for the Transmission of Borrelia recurrentis, the Agent of Relapsing Fever.

In recent years, bed bugs have reappeared in greater numbers, more frequently, and are biting humans in many new geographic areas. Infestations by these hematophagous insects are rapidly increasing worldwide. Borrelia recurrentis, a spirochete bacterium, is the etiologic agent of louse-borne relapsing fever. The known vectors are body lice, Pediculus humanus humanus. However, previous studies have suggested that bed bugs might also be able to transmit this bacterium. Adult Cimex lectularius were artificially infected with a blood meal mixed with bacterial suspension of B. recurrentis. They were subsequently fed with pathogen-free human blood until the end of the experiment. Bed bugs and feces were collected every 5 days to evaluate the capacity of bed bugs to acquire and excrete viable B. recurrentis using molecular biology, cultures, fluorescein diacetate and immunofluorescence assays. The feces collected on the day 5 and 10 postinfection contained viable bacteria. Immunofluorescence analysis of exposed bed bugs showed the presence of B. recurrentis in the digestive tract, even in bed bugs collected on day 20 after infection. Like human body lice, bed bugs can acquire, maintain, and excrete viable B. recurrentis that might infect humans through skin lesions. This preliminary work suggests that bed bugs might be competent vectors of B. recurrentis. Because bed bugs and body lice may share the same ecological niches, the role of bed bugs in transmitting recurrent fevers deserves further study.