Lyme Disease

1. Contracted when in endemic areas, early summer, when tick has been feeding (while embedded in you) for at least 24 hours
   - Stage 1: erythema migrans- expanding rash of a target lesion
   - Stage 2: early infection
   - Stage 3: late infection- oligoarticular arthritis

Diagnosis of lyme disease:

1. Don’t test unless you have an intermediate or high pretest probability
2. Test of choice is ELISA, followed by western blot. You can look at the IgM and IgG.
3. If you have a big joint to tap you can send PCR on the fluid
4. DO NOT SEND PCR on blood or urine- this is unreliable, and means little if positive

(Katharine Cheung MD, 12/13/10)