ABSTRACT
There are two recognized types of relapsing fever based on the species that serve as vectors of the disease organism to humans: louse-borne relapsing fever (LBRF) and tick-borne relapsing fever (TBRF). LBRF is caused by the spirochete Borrelia recurrentis and is transmitted by human body lice (Pediculus humanus), which also serve as a host reservoir (Figure 14.1). After being consumed as part of a blood meal by lice (louse is the singular form of lice), the spirochetes pass into the coelomic cavity where they multiply. Lice remain infected their entire lives, which can last several weeks. People become infected not by the bite of an infected louse, but when the louse is crushed by scratching, which releases spirochetes inside the louse and contaminates human skin. The spirochete can gain entry through cut or abraded skin or through mucous membranes (Goubau 1984).
