Diagnosis and Management of Lyme Disease - June 1, 2012 - American Family Physician
The article above is a solid summary of the current Lyme disease diagnosis and management principles. Here are a few pearls that caught my eye in this article.
1. As an ultra quick review, recall that typical Lyme has 3 stages. Stage 1 is early localized and includes erythema migrans and viral/flu like illness (fatigue, malaise, fever, chills, myalgia, headache). Obviously, most of our patients will present at this stage. Stage 2 is "early disseminated" Lyme, where the organism spreads to other organ systems from the tick bite site. Manifestations include cardiac (AV block, especially 3rd degree AV block), dermatologic (multiple, disseminated lesions of erythema migrans), musculoskeletal (arthralgias), and neurologic (facial nerve palsy, meningitis, encephalitis). Stage 3 includes arthritis and chronic neurologic issues, such as peripheral neuropathy.
2. Make sure to note the differentiation that the Stage 3 arthritis, which can occur months to years after a tick bite, is distinct from recently named, but not clinically validated, entities of "post Lyme disease syndrome" which is more of an unproven fatigue issue, and "chronic Lyme disease", which is currently a broad term of chronic patient issues that may or may not have Lyme disease.
3. Of vital importance to the Express Care physician in reassuring hysteric patients is that of all the tick diseases, Lyme is probably the hardest to transmit from tick to humans. The tick must bite, attach, feed until engorgement, then vomit the Lyme organism into the human bloodstream. The Borrelia bacterium actually lives in the midgut of the tick, and it must move via emesis into the tick salivary glands. Hence 2 vital items to document are how long the tick may have been attached (as Lyme usually takes 36 hrs of attachment to be transmitted), and whether the tick was engorged.
4.Symptoms of Stage 1 Lyme have been documented anywhere from days 3-30 after a bite, but the typical is 1-2 weeks after a tick bite.
5. As many as 80% of patients do develop the erythema migrans rash. Note that technically erythema migrans is a circular UNIFORM erythematous lesion with a range of 5cm to 70 cm. The CDC actually lists to diagnose erythema migrans an erythematous macule or papule at least 5 cm in size, with or without central clearing. In fact, only 19% of erythema migrans rashes develop the "ultra classic" bulls-eye rash. Patient and physicians can easily over focus on the central clearing, or lack thereof. The key is a red macule or papule at the bite 5cm or more.
6.Recall that the preferred indirect lab method by the CDC is the 2 step method where if the initial ELISA is positive, then a confirmatory Western blot assay be done. However, as the article displays in Table 3, the sensitivity in early localized Lyme with the 2-tier testing is still low, down to 17% sensitivity for acute phase early localized Lyme.
7. False postive labs also run rampant, as the IgM (surprisingly) and the IgG antibodies can remain in the serum for years even after (a resolved) infection. As such, the "usual aches and fatigue" can be mistakenly attributed to Lyme disease.
8. Treatment of early localized Lyme can be accomplished with doxycycline, amoxicillin, cefuroxime, and even azithromycin (which makes me wonder why Lyme has not been eradicated f rom the American population like smallpox has from the human population..just kidding).
Again, these were just a few of the useful Lyme reminders in this article. Check it out when you get a chance, and please add any additional observations below. Linwood
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