CHAPTER 36 Tick Removal and Prevention of Infection
Diseases Transmitted By Ticks
Ticks have eight legs and are members of the class Arachnida. Ticks belonging to the families Argasidae (soft ticks) and Ixodidae (hard ticks) are able to act as disease vectors to humans. The ixodid ticks Dermacentor and Ixodes are most likely to be encountered by humans in North America, and they can transmit microorganisms hematogenously during all phases of their development. See Box 36-1 for a list of tick-borne diseases.
Lyme disease is a fairly common illness affecting the cardiovascular, musculoskeletal, neurologic, and dermatologic systems. It is often seen in children and adults who spend time outdoors. Lyme disease is caused by the spirochete Borrelia burgdorferi, and is transmitted to humans by the bite of the hard Ixodes tick. White-footed mice and white-tailed deer are the major reservoirs for B. burgdorferi. This disease is becoming prevalent throughout northeastern North America, and is worth including in the differential diagnosis of unusual rashes, fevers, myalgias, and arthralgias. It is best diagnosed by enzyme-linked immunosorbent assay (ELISA) testing of serum for specific antibodies to B. burgdorferi. A Lyme disease preventative vaccine is now commercially available (LYMErix), and may be appropriate for those individuals living in high-prevalence locations who spend a great deal of time outdoors. Treatment of Lyme disease is discussed in the section on Complications and Disease Prevention. See Table 36-1 for a synopsis of presenting features of other tick-borne diseases.