Tick-borne diseases are diseases or illnesses transmitted by ticks. As the incidence of tick-borne illnesses increases and the geographic areas in which they are found expand, it becomes increasingly important that health professionals be able to distinguish the diverse, and often overlapping, clinical presentations of these diseases.

Tick-borne illnesses are caused by infection with a variety of pathogens, including rickettsia and other types of bacteria, viruses, and protozoa. Because ticks can harbor more than one disease-causing agent, patients can be infected with more than one pathogen at the same time, compounding the difficulty in diagnosis and treatment.

In general, specific laboratory tests are not available to rapidly diagnose tick-borne diseases. Due to their seriousness, antibiotic treatment is often justified based on clinical presentation alone.

Major tick-borne diseases include:

• Lyme disease
  • Organism: Borrelia burgdorferi
  • Vector: Ixodes scapularis (=I. dammini), I. pacificus
  • Region (U.S.): Northeast, Midwest, Mid-Atlantic West Coast
• Rocky Mountain Spotted Fever
  • Organism: Rickettsia rickettsii
  • Vector: Dermacentor variabilis, D. andersoni
  • Region (U.S.): East, South West
• Babesiosis
  • Organism: Babesia microti, B. equi
  • Vector: I. scapularis, I. pacificus
  • Region (US): Northeast West Coast
• Ehrlichiosis
  • Organism: Ehrlichia chafeensis, E. equi
  • Vector: D. variabilis, Amblyomma americanum, I. scapularis
  • Region (US): South-Atlantic South-Central
• Relapsing fever
  • Organism: Borrelia species
  • Vector: Ornithodoros species
  • Region (US): West
• Colorado tick fever
  • Organism: Coltivirus
  • Vector: D. andersoni
  • Region (US): West
• Tularemia
  • Organism: Francisella tularensis, A. americanum
  • Organism: D. andersoni, D. variabilis
  • Region (US): Southeast, South-Central, West, Widespread
• Tick paralysis
  • Cause: Toxin
  • Vector: D. andersoni, D. variabilis West
  • Region (US): East