The Curbsiders podcast

#105: Lyme Disease and Tick-Borne Illness with ID Expert Paul Sax: Why you should never go outside or to Boston in the summer

July 23, 2018 | By

Lyme disease and tick-borne illness deconstructed by Infectious Diseases expert, Paul E. Sax MD, of episode 78 fame. “Oh Summer Nights”. The time for romance between Danny Zuko and good girl Sandy, the time to sit in the backyard around the bonfire, the time for sunset hikes in the woods and mountains…..and don’t forget, it’s also the time for those pesky woodland ticks who’ll go for a ride on you and maybe suck your blood (gross!). Dr. Sax takes us through the essentials of tick-borne illness, with a focus on Lyme Disease: diagnosing it, treating it, identifying possible co-infections, and managing Post-Lyme residual symptoms.  

Our (And Dr. Sax’s) Disclaimer about this episode, and the shownotes: Tick-borne illness is a very serious problem in public health in the US, but management is quite a controversial issue. We’ve done our best with this episode to stay as evidence-based as possible. Moreover, given the limited time we have on air, we have tried to focus on what we think is most clinically relevant.

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Written by: Shreya P. Trivedi MD, Nora Taranto AB
Produced by: Shreya P. Trivedi MD, Nora Taranto AB
Editor: Matthew Watto MD
Images by:  Hannah R. Abrams
Hosts: Shreya P. Trivedi MD, Matthew Watto MD, Paul Williams MD
Guest: Paul E. Sax MD

Clinical Pearls

  1. A rash without central clearing DOES NOT EXCLUDE Lyme disease. Many times the erythema migrans rash in lyme disease does not have central clearing, but instead is gradually spreading, erythematous, and round–with or without central clearing.
  2. If the story fits (hiking or in the woods, in an endemic area, in the summer,  a roundish red rash in one or multiple places), have a high level of suspicion for Lyme. You can treat Lyme Disease without sending labs if suspicion is high. -Dr. Sax
  3. Limitations of lyme testing: enzyme immunoassay (EIA) IgM and IgG, with lyme disease has a high false positive rate (high sensitivity, but not specific). If EIA is positive or equivocal, a western blot IgG +/- IgM is recommended for confirmation (CDC on Lyme Testing). However, IgM western blot testing is also prone to false positives. -Dr. Sax
  4. Treatment of choice for Lyme Disease is Doxycycline (with Amoxicillin or Cefuroxime as a good section line option if patient cannot take Doxy), either 10 or 21 days.
  5. If a patient has a serious case of “the flu” in the middle of the summer and lives in an endemic area, test for the big three tick-borne illnesses–Borrelia (Lyme), Anaplasmosis, and Babesiosis. It’s an expensive panel, but one must be aware of co-infections. -Dr. Sax’s expert recommendation
  6. Distinguishing features of Anaplasmosis: it tends to be associated with high fevers, leukopenia, thrombocytopenia and is rarely seen with a rash.
  7. Distinguishing features of Babesiosis: it tends be associated with anemia and thrombocytopenia. Babesia parasites can be seen in red blood cells on a stained blood smear “parasite smear” (
  8. Post-lyme residual symptoms correlate with the severity of the initial infection, and with the delay in onset of treatment. There is no strong evidence that long-term antibiotic treatment will benefit people with post-residual symptoms. -Dr. Sax
  9. Provide prophylaxis for a tick bite (Doxycycline 200 mg) if the tick has attached. Consider prescribing doxycycline for post-exposure prophylaxis to those who live in hyperendemic areas and work outside. They should take a dose whenever they find a tick attached. -Dr. Sax’s expert recommendation
  10. Pant-tucking into socks, deet based insect repellent, and permethrin treated clothing are some of the best ways to avoid tick bites. Check yourself and your kids, and know where to look: behind the ears, collarbone, armpit, waistband, gluteal cleft, behind the knee, sock-band, even genitalia, anywhere the ticks can lodge and start feeding. -Dr. Sax

In-depth Show Notes

Case 1: The patient with a rash on his waistband, without central clearing, who went hiking, and is convinced it’s a spider bite:

  1. There’s a “Mass psychosis” that  staphylococcus abscesses are spider bites –Dr. Sax. Most “spider bites” that patients come in reporting aren’t spider bites. Most are actually staphylococcus abscesses  or Lyme disease, if the patient is in an endemic area in the summertime. (Dominguez TJ 2004)
  2. The sensitivity of erythema migrans is hard to estimate as lyme is often treated empirically. Be very leery of dismissing rashes as lyme during epidemiologic spikes –Dr. Sax
  3. Three endemic areas: 1. Northeast and mid-Atlantic, from northeastern Virginia to Maine 2. North central states, mostly in Wisconsin and Minnesota 3. West Coast, particularly northern California ( Dr. Sax notes that Lyme is moving south (e.g. the Carolinas), and can be found even in cities with community gardens/parks.
  4. Labs for Lyme:  Most patients with early Lyme don’t have positive PCR or Antibody. If presentation is atypical, send for labs (Borrelia Antibody, with reflex to more specific testing if positive)(CDC testing). However, be aware of the high rate of false positives, especially with the IgM Western Blot. A positive IgM in the presence of symptoms >3-6 months duration may be a false positive – Dr. Sax
  5. Can order PCR ONLY if the ability to generate antibodies is impaired (e.g. on Rituximab). However, the PCR sensitivities varies during the stages.
  6. There is no test of cure. There is no point to follow-up testing because serology may remain positive in those who have undergone treatment and become asymptomatic. -Dr. Sax’s expert opinion
  7. Treatment of choice: Doxycycline (also treats for. Anaplasma coinfection). If can’t take doxy: amoxicillin or cefuroxime orally (Pujalte 2013).
  8. Treatment duration: Poorly defined. Dr. Sax bases duration on patient tolerance of the antibiotic e.g. 10 days if poorly tolerated and 21 days if well tolerated.
  9. Doxycycline side effects to talk to patients about: 1. Skin Photosensitivity, especially in patients with less skin pigment 2. Pill esophagitis: patient should remain upright for at least an hour. 3. For high burden Lyme, warn against Jarisch-Herxheimer reaction, which is an immune response to killing of borrelia, with worsening of symptoms, high fever, chills, for 12-24 hours. Resolves with ibuprofen or acetaminophen.

Case 2a: The elderly patient who gardens, is outdoorsy, and has come down with the “flu”, with fever and rigors, in the middle of the summer in New England:  

  1. Fevers without a localizing source in an elderly healthy person are unusual and with a lot of outdoor activity,  tick-borne illness should be on the list. -Dr. Sax
  2. Think about the Big 3: Lyme Disease (borrelia burgdorferi, which is a spirochete), Anaplasmosis (rickettsial organism), Babesiosis (intracellular/erythrocytic parasite). Keep in mind co-infections may occur.
  3. In a case like this, send blood cultures, anaplasma PCR, babesia PCR, complete blood count with parasite smear, and Lyme antibody at the very least. This panel will be expensive. Do it anyway. – Dr. Sax’s expert opinion
  4. Risk factors for severe babesiosis: age, splenectomy/ poor splenic function, immunosuppression (e.g. on rituximab) (
  5. Treatment: For anaplasmosis: Doxycycline. For Babesiosis: combination of atovaquone and azithromycin. (IDSA 2006).
Figure 1: Curbsiders Tick-Borne-Ilness

Case 2b: The patient who is positive for Lyme Disease and Anaplasmosis, completes treatment, but still feels fatigued and “icky.” Does he have post-lyme residual symptoms?

  1. Post-Lyme Disease Syndrome (PLDS): A post-infectious constellation of symptoms in which patients had objective evidence of having Lyme, having been treated, and who are now having residual symptoms due to prior infection with Lyme but NOT due to living organisms in their system (CDC Post lyme disease syndrome).
  2. Post-Lyme Residual Symptoms correlate with severity of initial infection, especially with neurological involvement of lyme. It can also correlate with delay in onset of treatment.  But there is not strong evidence that longer treatment will benefit people (Halperin 2015).
  3. Dr. Sax rarely refers patients with PLDS to a neurologist, or for CSF examination (a workup that is usually unrewarding).
  4. Chronic lyme disease (CLD): A controversial, and poorly defined condition that attributes various non-specific symptoms (e.g. chronic pain, fatigue, neurocognitive and behavioral symptoms) to a protracted Borrelia burgdorferi infection. These cases often lack  “serologic evidence of Lyme disease”, and/or “plausible exposure to the infection.” Much of the controversy arises from the use of prolonged courses of antibiotics in the treatment of CLD. (Lantos PM. Chronic Lyme Disease. Infect Dis Clin North Am. 2015;29(2):325-340.)

Case 3: A patient found a tick behind her knee, and it’s attached.  

  1. Prophylactic Treatment? If a patient found a tick attached, give them a dose of 200 mg of doxycycline. This works well in reducing risk of lyme disease.
  2. How to take the tick off: Take tweezers, lift straight up. May have to use a little force. Don’t use a match, kerosene, etc. (Huygelen 2017)
  3. Ask about Dogs: Even if the patient was not in the woods, but the dog was, that can be a risk factor for infection.
  4. How to Prevent Lyme: Tucking long pants into socks is very effective. Use insect repellent (Deet based are most effective for ticks).  If a patient lives in an endemic area and spends a lot of time outside: Permethrin impregnated clothing and permethrin itself are very effective (Juckett 2013).

Goal: Listeners will learn about the lyme disease, the diagnosis, treatment, and prevention of lyme disease and other tick-borne illnesses, and effectively educate patients on tick related issues.

Learning objectives:
After listening to this episode listeners will…

  1. Recognize the classic presenting symptoms of Lyme Disease and be able to identify anatomic areas to look for tick bites when a rash is present.
  2. Identify the endemic areas of the country where Lyme Disease is found
  3. Manage post-exposure prophylaxis and treatment of Lyme Disease
  4. Differentiate among tick-borne illnesses
  5. Understand when to test for coinfection
  6. Explain the difference between Post-Lyme Residual Syndrome and Chronic Lyme Disease
  7. Educate patients about prevention of tick bites, and removal of ticks

Disclosures: Dr. Sax reports no disclosures. The Curbsiders report no disclosures.  

Time Stamps

  • 00:00 Intro
  • 02:17 Disclaimer
  • 03:19 Guest bio
  • 05:17 Getting to know Guest
  • 08:33 Favorite hiking experiences
  • 12:20 Disclaimer of Tick-borne illness
  • 12:28 Clinical case of recent hiking in endemic area with a rash
  • 20:59 Lyme testing limitations
  • 27:38 Patient education to doxycycline
  • 30:16 Case of elderly outdoorsy healthy male with flu-like symptoms in the summer
  • 32:39 Differentiating anaplasmosis and babesiosis
  • 33:17 Workup for patient with possible tick co-infections
  • 39:22  Post-lyme disease residual symptoms
  • 48:02  Case of tick attached to patient
  • 56:19  Outro

Links from the show:

  1. Centers for Disease Control and Prevention. “Post-treatment Lyme disease syndrome.” Retrieved from (2013).
  2. Pujalte GG, Chua JV. Tick-borne infections in the United States. Primary Care Clinical Office Practice. 40 (2013). 619-635:
  3. Halperin, John J. “Chronic Lyme disease: misconceptions and challenges for patient management.” Infection and drug resistance 8 (2015): 119.
  4. Huygelen et al. Effective methods for tick removal: a systematic review. J Evid Based Med. 2017. 10(3):177-188:
  5. Juckett G. Arthropod Bites. Am Fam Physician. 2013. 15;88(12):841-847:
  6. Dominguez TJ. It’s not a spider bite, it’s community-acquired methicillin-resistant Staphylococcus aureus. J Am Board Fam Pract. 2004;17(3):220–226:
  7. Russell FE, Gertsch WJ. For those who treat spider or suspected spider bites. Toxicon. 1983;21(3):337–339.
  8. Apply Bug spray AFTER sunscreen: Wang T, Gu X. In vitro percutaneous permeation of the repellent DEET and the sunscreen oxybenzone across human skin. J Pharm Pharm Sci. 2007;10(1):17–25:
  9. Lantos PM. Chronic Lyme Disease. Infect Dis Clin North Am. 2015;29(2):325-340:
  10. Wormser, Gary P., et al. “The clinical assessment, treatment, and prevention of Lyme disease, human granulocytic anaplasmosis, and babesiosis: clinical practice guidelines by the Infectious Diseases Society of America.” Clinical Infectious Diseases 43.9 (2006): 1089-1134.

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