Lyme disease /līm/ [Lyme, Connecticut, where originally described] , an infection caused by the spirochete Borrelia burgdorferi, transmitted by the bite of infected Ixodes ticks (which are far smaller than dog ticks). In the northeast and north-central United States and Canada, the ticks normally feed on the white-footed mouse, the white-tailed deer, or other mammals and birds. Ticks are most likely to spread infection after 2 or more days of feeding. Most commonly, nymph ticks spread the disease because they are smaller than 2 mm in size and are rarely noticed. In contrast, the larger adult ticks are more likely to be found and removed before they have transmitted infection. See also erythema migrans. ▪ OBSERVATIONS: The disease first manifests itself as a red skin macule or papule at the bite site with accompanying flulike symptoms, such as headache, fever, chills, muscle aches, and fatigue. These are often missed or ignored by the individual. In about 50% of cases, other lesions develop soon after onset. Lymphadenopathy, neck pains, and hepatosplenomegaly are also often present in early disease. After weeks or months, neurological abnormalities such as meningitis, meningoencephalitis, neuritis, and radiculopathies appear in about 15% of all cases. Myocardial abnormalities such as atrioventricular block, myopericarditis, and cardiomegaly occur in 8% of cases. Joint inflammation, pain, and arthritis develop in 50% of cases as long as 2 years after transmission. Diagnosis is made through clinical examination with evidence of characteristic lesions and a positive enzyme-linked immunosorbent assay (ELISA). Cultures and biopsy of skin lesions and PCR testing of blood give a definitive diagnosis. However, the lab tests are available only at reference laboratories. ▪ INTERVENTIONS: Current treatment centers around the use of oral or intravenous antibiotics. Treatment with appropriate antibiotics in the early stages of Lyme disease usually results in complete recovery. Antibiotics commonly used for oral treatment include doxycycline, amoxicillin, or cefuroxime axetil. Doxycycline is contraindicated in patients younger than 8 years and in pregnant women. ▪ PATIENT CARE CONSIDERATIONS: Care for acute disease is focused on rest and monitoring for complications. Education about preventive practices in endemic areas is needed and includes instruction to wear appropriate clothing (long pants tucked in boots) in wooded or grassy areas; use of bug repellent with DEET; keeping grass mowed; keeping woodpiles away from foot-traffic areas and the house; treating pets with tick and flea repellent and keeping pets off furniture; removal of ticks with tweezers; and thorough washing and application of antiseptic to any tick bite. Education is needed about the identification of the Ixodes tick and instruction to seek immediate treatment for any Ixodes tick bite or bull’s-eye–like rash.
