Lyme Disease

Basics

Description

  • Most common tick-borne illness in North America
  • Endemic in Northeast, Upper Midwest, and northwestern California

Etiology

  • Peak April–November; 80–90% in summer months
  • Spirochete Borrelia burgdorferi introduced by Ixodes tick:
    • Ixodes scapularis (deer tick) most common
    • Same tick that transmits anaplasmosis, babesiosis
  • Pathogenesis – combination of:
    • Organism-induced local inflammation
    • Cytokine release
    • Autoimmunity
  • No person-to-person transmission
  • Case numbers jumped 1.7× in 2022 from prior years due to a change in the case definition. Prior to 2022, reported cases had to include not only lab testing but also clinical investigation. In 2022, the case definition changed to allow for reporting with lab testing only in high-incidence areas

There's more to see -- the rest of this topic is available only to subscribers.