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ID: Lyme Disease
LTC Glenn Wortmann, MC, USA & MAJ Joseph Wilde, MC, USAIntroduction: Lyme disease is a tick-borne zoonotic infection caused by Borrelia burgdorferi. In the U.S., it
is most commonly found in the Northeast. It also occurs in Europe, Scandinavia, Russia, China, Japan and
Australia and is transmitted by the bite of an ixodid tick (deer tick), primarily during the summer months when
ticks are most active. The incubation period after a tick bite is 3-32 days.
Subjective: Symptoms
Early stage disease: Erythema migrans (circular, erythematous rash) at bite site in 75% of patients, with
multiple lesions present in 50% of patients; fever, Bell’s palsy, fatigue, malaise and cardiac abnormalities
(dropped beats, chest pain, pericarditis).
Later stage disease: Joint stiffness, myalgias, pain and swelling; headache; polyneuropathy; CNS neurological
problems (cerebellar ataxia, coma).
Focused History: Do you recall being bitten by a tick? (only 20-30 % recall bite) Do you recall the size of the
tick that bit you? (Lyme disease is transmitted by the small deer tick) How long ago were you bitten by a tick?
(The incubation period for erythema migrans is 3-32 days)
Objective: Signs
Using Basic Tools: Diagnostic rash of erythema migrans (EM) about 7 days after bite (see Color Plates
Picture 17); peripheral cranial nerve VII palsy (facial paralysis), bradycardia, fever, generalized adenopathy,
swelling in large joints (particularly knees), dropped heart beats, abnormal neurological exam.
Using Advanced Tools: EKG: Pericarditis, heart block. Serology testing is available for confirmation at most
hospitals but is often negative with early infection.
Assessment:
The rash of erythema migrans (EM) is diagnostic of Lyme disease.
Differential Diagnosis:
Erythema migrans - can be confused with cellulitis, arthropod bite, contact dermatitis, pityriasis rosea, tinea
corporis, drug reaction.
Plan:
Treatment: Acute infection (erythema migrans):
Primary: Amoxicillin 500 mg tid or Doxycycline 100 mg bid x 21 days.
Alternate: Clarithromycin 500 mg po bid x 14-21 days or azithromycin 500 mg po q day x 7-21 days
Neurologic infection: Penicillin 2 million units IV q 6h or ceftriaxone 30 mg/kg IV q d
Patient Education
General: Prevent tick bites, particularly in spring and early summer.
Activity: As tolerated. Avoid sun exposure while on doxycycline.
Diet: As tolerated
Medications: Occasional gastrointestinal side effects. Doxycycline should be avoided during pregnancy,
breastfeeding and in children.
Prevention and Hygiene: Personal protective measures (insecticide, etc.) against ticks.
No Improvement/Deterioration: Return for evaluation.
Follow-up Actions
Consultation Criteria: Failure to improve.
Zoonotic Disease Considerations