Syphilis

Syphilis is an infection that has intrigued scientists, baffled clinicians, and terrified patients for centuries. Although an inexpensive and highly effective treatment has been available for 60 years, syphilis continues to be a public health problem in both developed and developing parts of the world. The protean clinical manifestations, long periods of asymptomatic infection, and lifelong persistence of syphilis suggest a highly complex relationship between Treponema pallidum and the host's immune response. The extreme fragility of the causative bacterium and the inability to cultivate it in vitro have impeded progress in identifying and understanding the important virulence factors. The absence of an inbred animal model of syphilis and the consequent lack of immunological reagents complicate progress further. Despite these difficulties, the post-genomic era has yielded a new understanding of the molecular interactions of T. pallidum and the host. In this chapter, we present our current understanding of the mechanisms of syphilis pathogenesis in the context of a discussion of the clinical stages of syphilis.