Emerging bacterial infectious diseases/pathogens vectored by human lice

Human lice have always been a major public health concern due to their vector capacity for louse-borne infectious diseases, trench fever, louse-borne relapsing fever, and epidemic fever, which are caused by Bartonella quintana, Borrelia recurrentis, and Rickettsia prowazekii, respectively. Those diseases are currently re-emerging in the regions of poor hygiene, social poverty, or wars with life-threatening consequences. These louse-borne diseases have also caused outbreaks among populations in jails and refugee camps. In addition, antibodies to those pathogens have been steadily detected in homeless populations. Importantly, more bacterial pathogens have been detected in human lice, and some have been transmitted by human lice in the laboratory. Here, we provide a comprehensive review and update on louse-borne infectious diseases/bacterial pathogens.