LYME DISEASE

I. I.Epidemiology A. A.Originally described after cluster of cases of JRA (juvenile rheumatoid arthritis) – like disease in Lyme, CT in 1977 ; causative spirochete identified in 1982 B. B.Causative spirochete : Borrelia burgdorferi C. C.Tick vectors : deer ticks in USA ; (also field mice may harbor the ticks) a) a)Ixodes dammini in northeast and midwest b) b)Ixodes pacificus in west c) c)Ixodes ricinus (sheep tick) in Europe

LYME DISEASE I. I.Epidemiology (cont.) D. D.Demographics a) a)Infection has been acquired from every continent exept Antaractica b) b)The most common tick-transmitted illness in the USA (5,000 reported cases in 1988, with incidence increasing)

LYME DISEASE I. I.Epidemiology (cont.) D. D.Demographics (cont.) c) c)Most cases between May and August with peak in July d) d)3 main US endemic areas : Atlantic seaboard : Massachusetts  Maryland Upper midwest : Minnesota, Wisconsin Pacific coast : California, Oregon

LYME DISEASE II. II.Pathogenesis A. A.The tick requires a blood meal to pass into each of the 3 stages in its 2-year life cycle (from larva  nymph  adult). Humans are incidental hosts and are infected by the nymph. Borrelia reside in the midgut and are transmitted to the host via saliva or feces in the bite wound. Clinical illness from the spirochetes does not occur in wild animals but does in people, dogs, horses, and cattle.

LYME DISEASE II. II.Pathogenesis B. B.Early stage Lyme disease manifestations probably due to direct infection by the spirochete. Late stage symptoms and signs probably due to combination of infection and immune mechanisms triggered by spirochetal antigens.

LYME DISEASE III. III.Stages (asymptomatic subclinical infection also possible, up to 6 % in NE USA) A. A.Stage I (localized disease) 1. 1.ECM (erythema chronicum migrans) in 60 % (at the bite site) : annular, central clearing, warm, not painful, get redder in hot water 2. 2.Headache, myalgias (consider Lyme disease for “flu-like” sx in the summer) 3. 3.Arthralgias

LYME DISEASE III. III.Stages (cont.) B. B.Stage II (due to hematogenous dissemination of the spirochetes) 1. 1.Multiple / recurrent ECM : occurs at sites distance from the bite, nearly always less than 10 total lesions 2. 2.Borrelia lympocytoma : common in Europe ; bluish or purplish lesion on earlobe or areola. Requires biopsy to differentiate from Kaposi’s sarcoma

LYME DISEASE B. B.Stage II (due to hematogenous dissemination of the spirochetes) (cont.) 3. 3.Neurologic a) a)Aseptic meningitis : fairly common ; usually self-limited b) b)Peripheral neuropathies : 10 % may have Bell’s palsy (this may be the only sign of Lyme disease). Usually resolve without Rx in 2 to 3 months. c) c)Encephalitis (usually mild) d) d)Persistent headache 4. 4.May have mild migratory myalgias & arthralgias

LYME DISEASE B. B.Stage II (due to hematogenous dissemination of the spirochetes) (cont.) 5. 5.Cardiac a) a)AV block : occurs in 8 % ; may require temporary pacemaker ; usually resolves in one week b) b)Myopericarditis : less common 6. 6.Ophthalmic : conjunctivitis, iritis, panophthalmitis : uncommon

LYME DISEASE III. III.Stages (cont.) C. C.Stage III (due to immunologic reactions ± persistent infection) 1. 1.Acrodermatitis chronica atrophicans : common in Europe. Bluish-red “doughy” edematous skin on elbows, dorsum of hands and feet. Develops 5 to 10 years after ECM. Accompanied by sensory (more than motor) peripheral neuropathy in 45 %.

LYME DISEASE C. C.Stage III (due to immunologic reactions ± persistent infection) (cont.) 2. 2.Acute Lyme arthritis : develops in 60 % of untreated patients within 6 months. Knee and TMJ commonly affected. 10 to 20 % / year spontaneous remission rate Chronic Lyme arthritis : resembles refractory rheumatoid arthritis. All patients with this have high IgG titers. May need arthoscopic synovectomy for Rx.

LYME DISEASE C. C.Stage III (due to immunologic reactions ± persistent infection) (cont.) 4. 4.Neurologic a) a)Chronic meningoencephalitis : associated fatigue, peripheral neuropathy, and intellectual deficits b) b)Multiple sclerosis-like syndrome : but without hyperreflexia and bladder dysfunction and abnormal findings. Can see small lesions in white matter on MRI.

LYME DISEASE C. C.Stage III (due to immunologic reactions ± persistent infection) (cont.) 4. 4.Neurologic (cont.) c) c)Chronic encephalitis : may be progressive and not respond to Rx (due to immunologic mechanism) d) d)Sensorimotor neuropathies : may become chronic or persistent

LYME DISEASE III. III.Diagnosis A. A.Serology is improving and getting better standardized but in general Lyme disease is a clinical diagnosis. Lab dx relies on B cell produced antibody since the spirochetes are very difficult to culture. B. B.May cause false positive FTA – ABS for syphilis (but should be negative VDRL or RPR) C. C.IgM rises early but difficult to measure (if high, implies acute infection)

LYME DISEASE III. III.Diagnosis (cont.) D. D.IgG rises gradually and peaks at 12 months after infection but titers may remain elevated or measurable for life despite Rx E. E.IgG or IgM in CSF implies CNS infection F. F.ELISA is best test ; can be confirmed with western blot technique but this is expensive and time- consuming

LYME DISEASE IV. IV.Rx A. A.No evidence yet to recommend prophylactic antibiotics after a tick bite B. B.Stage I Rx Doxycycline 100 mg bid x 14 days (not for kids < 9 years old or pregnant patients) or Amoxicillin 500 mg 3 times a day (30 mg/kg/day) x 14 days or Erythromycin 500 mg 3 to 4 times a day (30 mg/kg/day) x 14 days (less effective) or cefadroxil 1 gram per day x 14 days or cefixime 400 mg per day x 14 days Some sources recommend initial Rx for 30 days and higher doses of Amoxicillin

LYME DISEASE IV. IV.Rx (cont.) C. C.Stage II Rx Oral or IV doxycycline or minocycline 100 mg bid Or IV penicillin 24 million units/day in 6 divided doses Or IV ceftriaxone 2 gm every 12 hr Or IV cefotaxime 3 gm every 4 hr D. D.Stage III Rx basically same as for Stage II E. E.If one course of antibiotics doesn’t work, should try patient on 1 to 2 additional courses of a different antibiotic

LYME DISEASE V. V.Prevention A. A.Light colored clothing ; keep skin covered when in brush or wooded areas B. B.Use tick repellants (0.5 % permethrin or permanone on clothing or 30 % DEET on skin) C. C.Remove ticks promptly : use forceps to grasp jaws of tick D. D.Diazinon spray in fall and spring will kill adult ticks