Identifying the vector of Lyme disease.

Lyme disease is the most common vector-borne illness in the United States. It is caused by the spirochete Borrelia burgdorferi, which is transmitted by the deer tick. Deer ticks have a four-stage life cycle (egg, larva, nymph, and adult), and nymphal ticks transmit B. burgdorferi to humans more frequently than adult ticks. Transmission of this spirochete typically requires a minimum of 24 to 48 hours of tick attachment. Early stages of Lyme disease are characterized by a hallmark rash, erythema migrans. The overall risk of acquiring Lyme disease is low in a person who has a deer tick bite. If erythema migrans develops at the site of the bite, treatment may include doxycycline in persons who are at least eight years of age. Administration of amoxicillin is appropriate for pregnant women or children younger than eight years. For those who are allergic to these medications, cefuroxime axetil may be used.