In the mid-1970s several dozen patients living near Lyme Connecticut developed an illness, initially misdiagnosed as juvenile rheumatoid arthritis, and subsequently called Lyme arthritis (Steere et al., 1977). It was renamed Lyme disease when its systemic nature was appreciated. In retrospect, skin and neurological manifestations of Lyme disease had been described in Europe for decades, and had even been recognized as antibiotic responsive (Coyle, 2000). Lyme disease is a multisystem infection due to the spirochete Borrelia burgdorferi. This spirochete, named after its discoverer Willy Burgdorfer, is present in hard body ticks of the Ixodes ricinus family (Burgdorfer, 1984). Ixodes ticks feed on a variety of hosts, including humans. Virtually all transmissions occur through tick bite, although there have been rare congenital cases. To date, there have been no documented blood transfusion cases (McQuiston et al., 2000). Lyme disease is one of the major emerging pathogen infections. It has generated significant publicity and controversy, and has become a focus of interest for both lay action groups and the popular press.

Spirochetal infection

B. burgdorferi is a spirochete. Spirochetes are gram negative bacteria that belong to a distinct eubacterial phylum (Benach & Coleman, 1993; Reik, 1987). They are flexible cells with a helical configuration, excessive length to diameter ratios of up to 100 to one, and flagella that lie between inner and outer cell membranes. These endoflagella convey motility properties. Of the four recognized human spirochetal infections which cause neurological disease, all show frequent central nervous system (CNS) seeding during the spirochetemic stage (Table 108.1). CNS infection may be inapparent, or associated with clinical disease. Spirochetes can also persist silently within the CNS, only to cause late neurologic problems months to years after initial infection. These spirochetal disorders have a number of features in common (Table 108.2). The shared features provide guidelines to think about Lyme disease

Organism

Borrelia spirochetes have coils which are spaced irregularly 2 to 4 micrometres (μm) apart (Benach&Coleman, 1993). B. burgdorferi is easy to culture from ticks, but difficult to culture frompatients.The spirochete is 11 to 39mcmlong.