Body and head lice (Pediculus humanus humanus and Pediculus humanus capitis, respectively) are typical ectoparasites of humans. They differ not only in the ecological habitat but also in the vector competence in spite of their conspecific nature. Only body lice transmit several bacterial pathogens to humans, including Bartonella quintana, Rickettsia prowazekii and Borrelia recurrentis. In this study, the proliferation rates of two model bacteria, a gram positive Staphylococcus aureus and a gram negative Escherichia coli, were determined following bacterial challenge by cuticular injection. Both bacteria proliferated rapidly in body lice at the early stage of bacterial challenge but not in head lice, suggesting that head lice have more sensitive immune responses to these bacteria. In vivo phagocytosis assay revealed that head lice have much higher phagocytic activity against E. coli than body lice whereas only slight differences in phagocytic activity against S. aureus were observed between the two lice species. Taken together, these findings suggest that the reduced phagocytosis activity of body lice contributes, at least in part, to their higher vector competence.

• Ju Hyeon Kim(Department of Agricultural Biotechnology, Seoul National University)
• Jee Sun Min(Department of Agricultural Biotechnology, Seoul National University)
• Young Ho Koh(Ilsong Institute of Life Science, Hallym University)
• Si Hyeock Lee(Department of Agricultural Biotechnology, Seoul National University)