A review for the emergency physician of this common tick-borne illness.
Hosts:
Audrey Bree Tse, MD
Brian Gilberti, MD



https://media.blubrry.com/coreem/content.blubrry.com/coreem/Lyme_Disease.mp3



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Tags: Infectious Diseases





Show Notes
Episode Produced by Audrey Bree Tse, MD

Background

* Most common tick-born illness in North America
* Endemic in Northeast, Upper Midwest, northwest California
* 80% to 90% in summer months

Pathophysiology

* Ixodes tick (deer tick) has a 3-stage life cycle (larvae, nymph, adult) & takes 1 blood meal per stage
* Deer tick feeds on an infected wild animal (infected with spirochete Borrelia burgodrferi) then bites humans
* On humans, they typically move until they encounter resistance (e.g. hairline, waistband, elastic, skin fold).  It takes 24-48 hrs for B. Burgdorferi to move from the tick to the host
* Pathogenesis: organism induced local inflammation, cytokine release, autoimmunity
* No person to person transmission

Clinical Presentation
Stage 1: Early

* Symptom onset few days to a month after tick bite
* Erythema migrans rash: bulls eye rash seen in more than 90% of patients with Lyme disease (Irregular expanding annular lesion(s))
* Regional adenopathy, intermittent fevers, headache, myalgias, arthralgia, fatigue, malaise

Stage 2: disseminated/ secondary

* Days to weeks after tick bite
* Intermittent fluctuating sx that eventually resolve
* Triad of aseptic meningitis, cranial neuritis, and radiculoneuritis: bell palsy most common
* Cardiac symptoms: tachycardia, bradycardia, AV block, myopericarditis

Stage 3: tertiary/ late

* Symptoms occur >1 year after tick bite
* Acrodermatitis chronic atrophicans: Atrophic lesions on extensor surfaces of extremities (resembles scleroderma)
* Monoarthritis, oligoarthritis (knee > shoulder > elbow)
* GI: Hepatitis, RUQ pain
* Ocular: keratitis, uveitis, iritis, optic neuritis
* Neurological: Chronic axonal polyneuropathy or encephalopathy

Chronic Lyme disease (versus well-accepted Lyme disease sequelae):

* Continuation of symptoms after antibiotics
* Current recommendation for management is supportive care only

Pediatric considerations:

* More likely to be febrile than adults
* Facial palsy accompanied by aseptic meningitis in 1/3
* Untreated kids can develop keratitis
* Excellent prognosis if appropriately treated

History

* Travel, camping, woods, playing under leaves or in wood piles
* Living in endemic area (Northeastern area: Maine to Virginia; upper Midwestern: Wisconsin, Minnesota; Northwest California)
* Endemic in Northern Europe and Eastern Asia as well
* History of tick bite (- 30-50% of patients recall tick bite)