Show Notes
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,