A Quick Tour of the New Lyme Disease Guideline

Paul G. Auwaerter, MD


June 14, 2021

This transcript has been edited for clarity.

Hello. This is Paul Auwaerter for Medscape Infectious Diseases, speaking from Johns Hopkins University School of Medicine. Spring is in full swing and tick season has certainly returned. I thought I would briefly go over new information that was incorporated into the most recent Lyme disease guideline, published late in 2020.

In contrast to the 2000 and 2006 guidelines from the Infectious Diseases Society of America (IDSA), this particular guideline is co-sponsored by three professional societies: the IDSA, the American Academy of Neurology, and the American College of Rheumatology. There were 33 authors in all (I was one of them), representing not only infectious diseases but also primary care, family practice, internal medicine, cardiology, and emergency medicine. We even had a representative from the Entomological Society of America. So the guideline includes broad perspectives. Following the National Academy of Sciences recommendation, this guideline uses the rigorous GRADE format to label the strength of the evidence. Not a tremendous amount has changed, but items that may be useful for your clinical practice are as follows.


For prevention, unfortunately we're still left with tick checks, wearing long sleeves and pants, and using repellents. If the Ixodes scapularis tick — the black-legged tick — is embedded for more than 36 hours, appears engorged, and is in an area with a high endemicity for Lyme disease, one could consider single-dose doxycycline for prevention, or observation for symptoms.


The diagnosis sections are more thorough than in earlier iterations of Lyme disease guidelines, but it still boils down to the rash, erythema migrans being the most common way to identify early Lyme disease. Later manifestations without a cogent skin lesion history would mean that you have to rely on serologic evidence. Of importance, the guideline goes out of its way to cite the lack of evidence for performing Lyme disease tests, specifically routine testing in cases where there's no evidence or link to Lyme disease. Examples include someone who is asymptomatic after a tick bite, even when they have a neurologic condition such as amyotrophic lateral sclerosis, multiple sclerosis, Parkinson's disease, dementia, or any kind of new-onset seizures or psychiatric illness. In children, behavioral and developmental disorders don't warrant assessing a Lyme disease serology. This also includes anyone with long-term cardiomyopathy of unknown cause.

Lumbar punctures are not routinely advocated when you have a positive serology in patients with, for example, a facial palsy. However, if a lumbar puncture is pursued, often in emergency room settings, when looking for other diagnoses that could be causing a meningitis (Lyme can cause an aseptic meningitis), a cerebrospinal fluid index is one way to be more certain of significant intrathecal antibody production.

With late Lyme arthritis, characteristically manifested by a swollen knee joint, if you have a positive serology, you do not have to perform an arthrocentesis. Of course, if there’s a characteristic picture and you need to rule out gout or septic arthritis, you should by all means do that. If there's any confusion, you can always obtain a Borrelia burgdorferi PCR test from the synovial sample. Synovial fluid is one of the few — perhaps the only — sample that has sufficient yield on PCR testing.

Last, I want to mention Southern tick-associated rash illness, or STARI. We do not yet know the etiology of STARI. It is associated with the bite of the lone star tick, also known as Amblyomma americanum. Typically, these ticks were found in areas where Lyme disease was not considered endemic, but the geographic range of this tick has spread in the past decade or so. Now they are found in overlapping areas, providing diagnostic confusion. So we have a clear need to try to understand the cause of STARI and perhaps develop different diagnostic tests than for Lyme disease.


The duration of treatment for erythema migrans, early Lyme disease with the skin lesion, is 10 days of doxycycline, based on two studies showing that this was as effective as longer treatment (Stupica and colleagues; Wormser and colleagues). There are no such shorter-duration studies for amoxicillin or cefuroxime, so the recommendation for duration of treatment with these remains at 14 days.

Doxycycline is now an option for treating children under the age of 8 years. It appears that doxycycline doesn't result in the dental enamel staining that the older forms of tetracycline, such as chlortetracycline or tetracycline, did, so short-course doxycycline therapy does not pose concerns. Finally, nearly all kinds of outpatient Lyme disease can be treated with doxycycline. There's no need for parenteral therapy. The only exception may be for encephalomyelitis, a now uncommon condition of late neurologic borreliosis.

I hope this quick tour of the new guideline will be useful for your practice. You can certainly turn to the document for its many recommendations and the thorough evidence base. I hope this will help in your care of patients during the tick season.

Thanks so much for listening.

Paul G. Auwaerter, MD, is a professor of medicine at the Johns Hopkins University School of Medicine and clinical director of the Division of Infectious Diseases. His areas of clinical expertise include Lyme disease, Epstein-Barr virus, and fever of unknown origin. He has been a Medscape contributor since 2008.

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