Internal Medicine

0521779407-13 CUNY1086/Karliner 0 521 77940 7 June 4, 2007 21:15

Lung Fluke Lyme Disease 927

mimic appendicitis, diverticulitis, etc., and surgery is sometimes

indicated to make diagnosis. After treatment, prognosis is good,

though residual neurologic signs may exist, and scarring remains

in lungs.

LYME DISEASE

RICHARD A. JACOBS, MD, PhD

history & physical

History

■In the US, caused byBorrelia burgdorferi, an aerobic Gram-negative

bacillus (B. gariniiandB. afzeliiagents in Europe and Asia)

■Transmitted by Ixodes ticks (the black-legged tick); Ixodes scapu-

laris vector in New England, mid-Atlantic and upper Midwest;Ixodes

pacificusvector on West Coast

■Ticks infected by feeding on white-footed mouse or deer, the natural

reservoirs forB. burgdorferi

■Risk of transmission to humans depends on stage of tick (nymphs

and adults more likely to transmit disease than larvae), geographic

location (15%–65% of ticks infected in Northeast and Midwest, but

only 1%–3% of ticks in Western US infected) and duration of feeding

(ticks must feed at least 48 hours to transmit organism)

■Over 90% of cases reported from southern New England, the mid-

Atlantic states and the upper Midwest; smaller endemic area exists

along northern Pacific coast

Signs & Symptoms

■Early localized disease-80% have erythema migrans, a flat or slightly

raised, nontender, erythematous lesion that expands over days to

weeks, often but not invariably, with central clearing; begins 7–10

days after bite (range 3–30 days) and clears spontaneously even with-

out therapy; associated fevers, chills myalgias present in about 50%

■Early disseminated disease-usually occurs several weeks to months

after tick bite and can involve skin, the nervous system or the heart;

multiple erythema migrans lesions develop in 50%; myopericardi-

tis with arrhythmias or heart block seen in 4%–10%; neurologic

involvement (10%–20%) usually manifests as aseptic meningitis with

mild headache or Bell’s palsy, but peripheral neuropathy (sensory or

motor) and eye disease (optic neuritis, iritis, keratitis, conjunctivitis)