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Wise Use of Antibiotics: Top 6 Tips and Tricks for Treating Ticks

Column Author: Ann Wirtz, PharmD, BCPPS | Adjunct Clinical Associate Professor of Pharmacy, University of Missouri-Kansas City School of Pharmacy

Column Author: Rana El Feghaly, MD, MSCI | Director, Infectious Diseases Clinical Services; Director, Outpatient Antibiotic Stewardship Program; Medical Director, Vaccines for Children (VFC) Program

 

Summertime is finally here! While warm weather brings opportunities for outdoor fun such as picnics, hiking and camping, we also observe a rise in tickborne infections. The Centers for Disease Control and Prevention (CDC) reports that emergency department visits for tick bites in the United States have increased significantly since April, especially in the Midwest.1 Recently, the Kansas Department of Health and Environment published a healthcare alert on the increased tick activity and reports of tickborne diseases in our area (accessed here). Therefore, pediatric clinicians should be aware of the tips and tricks with treating tickborne infections.  

Tip 1: Lyme disease is uncommon in Kansas and Missouri.

The most common types of tickborne infections occurring in Kansas and Missouri are ehrlichiosis and Rocky Mountain spotted fever (RMSF), which will be the focus of this article. Ehrlichiosis is predominantly caused by Ehrlichia chaffeensis or less commonly Ehrlichia ewingii, both transmitted by the lone star tick. RMSF results from infection with Rickettsia rickettsii, transmitted primarily by the American dog tick in eastern/central U.S.2-4 Tularemia is also occasionally seen in our states, and most often presents with lymphadenopathy +/- skin ulceration at the site of the bite.

Lyme disease is caused by Borrelia burgdorferi or B. mayonii. While one of the most widely recognized tickborne infections, Lyme disease is uncommon in most Midwestern states (including Kansas and Missouri). Approximately 90% of cases of Lyme disease are reported in the Northeast, mid-Atlantic, and upper-Midwest regions.5Therefore, consider this diagnosis only in patients with a clear epidemiologic link and signs and symptoms consistent with Lyme. Testing for Lyme disease is not indicated for early localized (i.e., erythema migrans) disease, where treatment is indicated without testing if suspected. The two-step testing algorithm for Lyme disease should be performed only in patients with a travel history to endemic areas and who present with signs and symptoms consistent with early disseminated (e.g., multiple erythema migrans, cranial nerve palsies, carditis) or late (i.e., arthritis) Lyme disease.

Tip 2: Symptoms can be nonspecific and may not always include a rash.

Nonspecific signs and symptoms of ehrlichiosis or RMSF may mimic other childhood illnesses.6 Early symptoms may include fever, myalgia, headache, gastrointestinal symptoms, and malaise. With ehrlichiosis, approximately 60% of children (but <30% of adults) develop a rash. With RMSF, patients typically develop a maculopapular rash which begins on the wrists and ankles and spreads to the trunk. As illness progresses to severe disease, the rash becomes petechial. The rash may be absent in 10% of patients with RMSF. Initial laboratory findings may include leukopenia (particularly lymphopenia with ehrlichiosis), thrombocytopenia, hyponatremia and elevated hepatic transaminase levels. If left untreated, symptoms may progress to severe multiorgan dysfunction with respiratory distress, shock, encephalopathy, disseminated intravascular coagulation, meningitis and renal/hepatic failure.3,7

Tip 3: Avoid ordering tickborne panels, particularly in the outpatient settings.

Clinicians should have a high level of suspicion for these infections in the summer months, even if an exposure to a tick is not confirmed. The diagnosis is typically made clinically and confirmed later. For ehrlichiosis, a polymerase chain reaction (PCR) test of whole blood is sensitive especially if done prior to antibiotic administration. The gold standard for diagnosing RMSF is a positive indirect fluorescence immunoglobulin (Ig) G for RMSF. Since serology does not show an increase until seven to 10 days in the disease course, a negative early test does not rule out the diagnosis, which can be confirmed by a fourfold rise in titers in convalescent serum two to four weeks later.6 It is important to not send tickborne panels as a routine test in children presenting with nonspecific symptoms. These tests are costly and carry a high risk of misinterpretation. In addition, a negative test does not rule out a tickborne illness, particularly early in the infection; and a positive test does not confirm the diagnosis as low-level elevated antibody titers can be found incidentally in a high proportion of the general population in our region.

Tip 4: If you are concerned, treat the patient. Do not wait for test results.

For patients with a possible or suspected RMSF or ehrlichiosis, treatment should be initiated immediately. Retrospective studies demonstrated that patients with RMSF who received treatment within five days of symptom onset have significantly less mortality than those who received treatment after five days (6.5% vs. 22.9%), highlighting the substantial impact of rapid treatment initiation.8 Delays in treatment occur more often due to delay in clinician prescribing rather than delays in seeking medical care.6,7 

Tip 5: Doxycycline is the drug of choice and is safe for use in children.

Doxycycline is the treatment of choice for all age groups for ehrlichiosis and RMSF. Alternative agents are less efficacious. Patients should be treated for at least three days once afebrile and until clinical improvement, usually five to seven days.4 Many pediatricians continue to be hesitant to prescribe doxycycline in children under 8 years old due to concern for tooth discoloration associated with older tetracyclines. Tetracyclines readily bind to calcium ions within teeth, resulting in yellow, gray or brown staining if given during tooth calcification or mineralization.9,10 In a 2012 survey, only 35% of providers chose doxycycline as the treatment of choice in children <8 years old for RMSF.9 Doxycycline, which was developed later, binds less readily to calcium than tetracycline. Studies have not found an association between doxycycline use and tooth discoloration in children <8 years old.10 The American Academy of Pediatrics Committee on Infectious Diseases reports that doxycycline may be used for durations of 21 days or less without regard to patient age.4 Therefore, doxycycline should be used to treat children of all ages with concern for ehrlichiosis or RMSF.

Photosensitivity reactions, manifesting as painful or itchy sunburn-like eruption, may occur in 4%-10% of patients receiving doxycycline when exposed to the sun or other ultraviolet light. It is essential to discuss using sunscreen and protective clothing with patients to prevent this reaction.11,12 Due to interactions with divalent cation-containing compounds (calcium, magnesium, iron, zinc, etc.), doxycycline should be spaced away from oral medications containing these components, such as multivitamins. Esophagitis may occur due to local caustic injury to the esophagus; taking the medication with a large amount of fluid and avoiding lying down immediately after ingestion may help prevent this injury.12

Tip 6: There is no indication for antibiotic prophylaxis if a tick is found on a child in our region.

The only tickborne illness where antibiotic prophylaxis has been shown to be efficacious is Lyme disease. A one-time dose of doxycycline would be indicated if a patient is found to have an engorged (has fed >36 hours) Ixodes scapularis tick in an area endemic for Lyme, and prophylaxis can be initiated within 72 hours of tick removal. For the common tickborne illnesses found in our region, prophylaxis is not indicated; parents should be advised to seek care if signs and symptoms concerning for tickborne illnesses occur after the tick is found. The incubation period for RMSF is three to 12 days, and for ehrlichiosis is four to 14 days.

As patients spend more time outside during the warmer months, clinicians should consider tickborne infections on their differential diagnosis for patients presenting with nonspecific signs and symptoms to avoid delays in diagnosis. Additionally, to prevent infection, clinicians should counsel patients on appropriate prevention and tick removal strategies. These can be found on the CDC website, which includes an interactive tool, the Tick Bite Bot, to help with removing ticks and advising on when to seek care.  

References:

  1. Tick bite data tracker. Centers for Disease Control and Prevention. May 15, 2024. Accessed May 22, 2024. https://www.cdc.gov/ticks/data-research/facts-stats/tick-bite-data-tracker.html
  2. Centers for Disease Control and Prevention. Tickborne Diseases of the United States: A Reference Manual for Healthcare Providers. 5th ed. U.S. Department of Health and Human Services, Centers for Disease Control and Prevention; 2018. https://www.cdc.gov/ticks/tickbornediseases/TickborneDiseases-P.pdf
  3. Read JS. Tickborne diseases in children in the United States. Pediatr Rev. 2019;40(8):381-397.
  4. American Academy of Pediatrics. Committee on Infectious Diseases. Red Book: 2024 Report of the Committee on Infectious Diseases.33rd ed. American Academy of Pediatrics; 2024.  
  5. Kugeler KJ, Earley A, Mead, PS, Hinckley AF. Surveillance for Lyme disease after implementation of a revised case definition – United States, 2022. Weekly. 2024;73(6):118-123.
  6. Buckingham SC. Tick-borne diseases of the USA: ten things clinicians should know. J Infect. 2015;71 Suppl 1:S88-96.
  7. Binder AM, Armstrong PA. Patient characteristics, treatment patterns, and outcomes of Rickettsial diseases among a commercially insured population in the United States, 2005-2017. Sci Rep. 2021;11:18382.
  8. Kirkland KB, Wilkinson WE, Sexton DJ. Therapeutic delay and mortality in cases of Rocky Mountain spotted fever. Clin Infect Dis. 1995;20(5):1118-1121.
  9. Centers for Disease Control and Prevention. Research: doxycycline and tooth staining. Accessed April 20, 2022. https://www.cdc.gov/rmsf/doxycycline/index.html
  10. Todd SR, Dahlgren FS, Traeger MS, et al. No visible dental staining in children treated with doxycycline for suspected Rocky Mountain spotted fever. J Pediatr. 2015;166(5):1246-1251.
  11. Goetze S, Hiernickel C, Elsner P. Phototoxicity of doxycycline: a systematic review on clinical manifestations, frequency, cofactors, and prevention. Skin Pharmacol Physiol. 2017;30(2):76-80.
  12. In: Lexi-Drugs. Lexicomp; 2022. Updated April 19, 2022.  https://online.lexi.com
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