The Cribsiders podcast

#103: Tick-Talk: A Deet-ailed Look at Tick-Borne Illnesses

February 14, 2024 | By

Audio

Summary:

Dr. Buddy Creech of  Vanderbilt teaches us the core signs and symptoms of tick-borne illnesses, the importance of geographic variation in making a diagnosis, why doxycycline is the drug of choice for treatment, and not just what but also why we see lab abnormalities in Ehrlichiosis.


Tick-Borne Illnesses Pearls

  1. Fever, photophobia, headache, arthralgias, and rash without respiratory symptoms or sick contacts are classic symptoms that can be found in tick borne illnesses.
  2. Use the mnemonic ‘PLATES’ to take an ID history: Pets, Lifestyle, Appetite, Travel, Exposures, Sexual history.
  3. Lab findings such as lymphopenia, thrombocytopenia, and hyponatremia are common in tick-borne illnesses.
  4. Lab confirmation of tick-borne illnesses is not necessary for treatment. A clinical diagnosis can and should be made to provide effective and timely treatment.
  5. Doxycycline is the drug of choice for treatment of tick-borne illnesses and is safe for use in pediatric patients.
  6. Consider geographic distributions of tick-borne illnesses to narrow your differential. Lyme = NE, upper Midwest, and Atlantic seaboard. Rickettsial diseases = SE, Midwest, and Rocky Mountains.  
  7. Prevention of tick-borne illnesses is primarily through prevention of tick bites. This includes DEET, permethrin, and picaridin


Tick-Borne Illnesses Notes 

Taking a Tick History

How to take an ID history using PLATES: 

Pets: Dogs, cats, and everything else that your patient loves

Lifestyle: Inside/Outside, x-box or woodland adventures

Appetite: Dirt, Pica, unpasteurized or exotic foods

Travel: domestic and abroad

Exposure: known exposures to communicable diseases

Sexual history: when applicable, but it’s applicable more than you’re asking

Geographic distribution dictates the likelihood of tick borne disease. This is specifically due to the regional nature of the infectious vectors. The CDC has great maps to show what is prevalent in your area.

Oftentimes, ticks exposures are not actually known. As Dr. Creech noted, there’s always a tick even if the patient doesn’t remember removing one themselves. Similarly, it is estimated that many minor diseases (in the right areas) may be a presentation of tick-borne diseases. In Dr. Creech’s expert opinion, it is OK to empirically treat in the summer in the right clinical setting.

(Note, Dr. Creech stated there’s also always a cat, but Bartonella is out of the scope of this episode)

Diagnosing Tick Borne Diseases:

Skin Findings by Disease:

RMSF: Macules on wrists and ankles, often on palms and soles. Starts on the extremities then spreads inwards. Simultaneous with disease onset.  *Most classic rash

Ehrlichiosis: Similar to RMSF, though palms and soles can be spared.  Rash is more common in children– up to 80% of pediatric patients– and less common in adults.

Lyme: Erythema migrans (target-like lesion) localized around area of tick bite

Expert opinion: In an otherwise convincing clinical setting, Dr. Creech does not withhold treatment  because the patient does not have a rash.

Laboratory Findings Suggestive of Tick Borne Diseases:

In General, look for lymphopenia, thrombocytopenia, hyponatremia, elevated liver enzymes.

Rickettsial diseases (Ehrlichia and Rickettsia) cause vasculitis which can lead to SIADH and DIC, causing the findings of hyponatremia and thrombocytopenia. Ehrlichia classically presents with elevated liver enzymes.

Treatment (Doxycycline. That’s it. That’s the Tweet.)

Doxycycline is the mainstay of treatment for all tick borne diseases.

Because we do not have a timely and effective serologic diagnosis, diagnosing tick borne illness is a clinical diagnosis. Moreover, the mortality for Ehrlichia and Rickettsia increases after 4 days without treatment. Empiric coverage may be given to patients with sepsis if time of year and location fits. 

The treatment course is quite simply “treat until a couple days beyond symptom improvement” for Rickettsial illnesses. Lyme disease treatment is typically 2 weeks.

Doxycycline Notes

Side effects of doxycycline include pill esophagitis, GI upset, and sun sensitivity. 

Tooth discoloration was associated with tetracycline but is not known to be a side effect of doxycycline. This side effect has been removed from the Red Book as has the contraindication of doxycycline in children.

True contraindications: pregnancy, breastfeeding, if the patient is allergic to doxycycline

Amoxicillin may be used in children with proven doxycycline hypersensitivity. Duration of treatment with amoxicillin is extended to 3 weeks for patients with Lyme disease.

Lyme Disease Follows Its Own Path:

Unlike other tick borne illnesses which either get better or get significantly worse, Lyme disease, caused by the spirochete Borrelia burgdorferi, acts strangely and has multiple phases. Because it is challenging to test for, we deal with it separately here.

Lyme phases:

  • Early Localized: erythema migrans
  • Early Disseminated: flu-like illness
  • Mid/late: Carditis, facial palsy, culture negative lymphocytic meningitis
  • Late finding: Septic arthritis

Similar to other tick borne diseases, doxycycline is always the drug of choice for Lyme, with the exception of pregnancy and CNS disease, for which ceftriaxone is used. Duration is related to the response to treatment.

Lyme confirmatory testing: two-tiered approach with ELISA first, then confirmed with Western Blot. The first test is sensitive, the second test is specific. Providers may only see positive or negative test results. Families may also see results before providers do. When sending these tests, Dr. Creech typically tells families that testing is complicated and will need expertise to interpret.

Lyme prophylaxis may be given in high endemic areas (Zhou et al., 2021) if these criteria are met:

  • Endemic area
  • Engorged Tick
  • Black legged/Ixodes tick
  • Doxycycline is otherwise clinically safe (not pregnant or breastfeeding)

Dose for prophylactic doxycycline is one “double-dose”:

  • 200mg for adults
  • 4.4mg/kg for children

Co-infections

Babesiosis is associated with Lyme disease, though is very rare. Consider babesiosis when the previously diagnosed disease (like Lyme) is not responding to typical therapies. Risk factors to babesiosis include asplenia, immunocompromised, chronic liver or kidney disease. Babesiosis treatment is similar to malarial disease.

One last coinfection is that of skin flora. A tick bite is a break in the skin, which can introduce skin flora to deeper tissues causing, for example, cellulitis.

Removal

Remove ticks with tweezers when found. Apply gentle pressure to remove the entirety of the tick. Try to avoid bursting the tick! 

Prevention

Understand the geographic distribution of tick-borne illnesses to know when to implement prevention strategies– tick bites are more common in overgrown areas, less common in cities and fairways.

Chemical bug repellent is effective, especially deet. Treat clothes with permethrin. Other tick prevention chemicals/compounds include picaridin, lemon oil, and eucalyptus. And, as a fail-safe, perform tick checks. Look at the hairline, axilla, and skin folds. Assess your clothes for ticks and wash your clothes when done exploring.


Goal

Listeners will explain the history, exam, and lab findings of tick-borne illnesses and apply management and prevention techniques to their counseling of patients who may encounter tick exposures. 

Learning Objectives

After listening to this episode listeners will…  

  1. Perform effective history taking and physical exams specific to identifying tick-borne illnesses.
  2. Be familiar with the lab findings associated with tick-borne illnesses and the pathophysiology behind these findings.
  3. Recognize the importance and safety of doxycycline as the primary medicine for managing tick-borne illnesses. 
  4. Describe the stages of Lyme disease.
  5. Counsel patients on the most effective strategies for preventing tick bites.

Disclosures

Dr Creech reports a consulting fee for CommenseBio, GSK, TDCowen, and AstraZeneca. The Cribsiders report no relevant financial disclosures. 

Citation

Hanson RM and Ward B, Creech CB, Masur S, Chiu C, Berk J. “#103: Tick Talk: A Deet-ailed look at Tickborne Illnesses”. The Cribsiders Pediatric Podcast. https:/www.thecribsiders.com/ February 14, 2024.


 

Episode Credits

Written and Produced by: Ryan Hanson MD; Brian Ward MD
Showrunner: Sam Masur MD
Infographic: Brian Ward MD
Cover Art: Chris Chiu MD
Hosts: Justin Berk MD MPH MBA and Chris Chiu MD
Editor: Clair Morgan of nodderly.com
Guest(s): Buddy Creech MD MPH

CME Partner

vcuhealth

The Cribsiders are partnering with VCU Health Continuing Education to offer FREE continuing education credits for physicians and other healthcare professionals. Visit cribsiders.vcuhealth.org and search for this episode to claim credit.

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