Wise Use of Antibiotics: Tickborne Illnesses

Column Author: Morgan Vaughn, MD, FAAP | Clinical Assistant Professor of Pediatrics, University of Missouri-Kansas City School of Medicine; Education Assistant Professor of Pediatrics, University of Kansas School of Medicine

Chris Day, MD | Medical Director, Immune Compromised Service & Special Immunology Clinic, Infectious Diseases; Medical Director, International Travel Clinic, Infectious Diseases; Medical Director, Travel Medicine Program,Assistant Professor of Pediatrics, University of Missouri-Kansas City School of Medicine; Clinical Assistant Professor of Pediatrics, University of Kansas School of Medicine

Column Editor: Rana El Feghaly, MD, MSCI | Associate Chair, Ambulatory & Regional Quality Improvement, Department of Pediatrics; Director, Outpatient Antimicrobial Stewardship Program; Director, Infectious Diseases Clinical Services; Medical Director, Vaccines for Children (VFC) Program, Professor of Pediatrics, University of Missouri-Kansas City School of Medicine; Clinical Assistant Professor of Pediatrics, University of Kansas School of Medicine

Summertime brings a change in chief complaints and reasons for sick visits. We see more injuries, rashes and insect bites. This is a great time to review our approach to tick bites and tickborne illnesses, which increase in prevalence from April to September.¹ What should raise our suspicions for a tickborne illness? How should we evaluate and treat these patients? The Department of Evidence Based Practice at Children’s Mercy recently created a clinical pathway to help practitioners when there is a suspicion for certain tickborne illnesses relevant to our area. This article will give a quick overview of the pathway as a refresher as we head into summer and tick season!

Which Tickborne Illnesses to Consider in Our Area?

The most common causes of tickborne illnesses in Kansas and Missouri include ehrlichiosis, Rocky Mountain spotted fever (RMSF) and tularemia.² Tickborne illness should be considered in the differential diagnosis of a child with fever, even in the absence of a rash. Recreational activities that increase exposure to ticks and known or assumed tick bites in the past two weeks should also raise our suspicions.

Diagnosing and Managing RMSF and Ehrlichiosis

RMSF is caused by the bacteria Rickettsia rickettsii and in our region is spread by the American dog tick.³ Ehrlichiosis, caused by any of several related bacteria (Ehrlichia chaffeensis, E. ewingii or E. muris eauclairensis), is carried in Kansas and Missouri primarily by the lone star tick.⁴ In addition to fever, the signs and symptoms of Ehrlichiosis and RMSF can include a rash, headache, muscle aches, malaise, hypotension, nausea and vomiting. The rash of RMSF typically appears two to four days after the onset of fever. It usually begins as small, pink macules often starting on the ankles, wrists and forearms and can then spread to the trunk. Palms and soles typically become involved later in the illness. The rash can turn petechial on day 5 or 6 of illness, which is a sign of progression to more severe disease.³ The rash in ehrlichiosis occurs in about 60% of children with the disease. The rash is non-specific and may vary from maculopapular to petechial. It often occurs about five days after fever onset.⁴

If there is concern for RMSF or ehrlichiosis, basic laboratory evaluation is the appropriate next step. We recommend obtaining a complete blood count, a basic metabolic panel and liver function tests to start. Findings that may suggest tickborne illnesses include thrombocytopenia, leukopenia, hyponatremia, elevated AST and ALT, and hyperbilirubinemia. If you’re still considering RMSF or ehrlichiosis, specific testing such as RMSF IgG/IgM, ehrlichia antibody panel and ehrlichia PCR can be obtained, but do not wait for the results to initiate empiric treatment. Doxycycline is the treatment of choice for all ages for both RMSF and ehrlichiosis (dosing: oral, IV 2.2 mg/kg/dose every 12 hours daily for five to seven days; maximum dose: 100 mg/dose). We recommend consulting an infectious diseases expert with any questions.⁵

Diagnosing Tularemia

Tularemia is caused by the bacterium Francisella tularensis. It can be spread by several kinds of ticks as well as by deer flies. Infections also occur from handling infected animals and by inhaling dust or aerosols containing the bacteria.⁶ In our region, tularemia in a child most often presents as tender lymphadenopathy, either with an accompanying ulcer or without an ulcer, that is unresponsive to usual antibiotics. Other presentations include conjunctivitis with preauricular adenopathy and community-acquired pneumonia unresponsive to typical antibiotics. Tularemia serology is typically the preferred modality for diagnosis. The microbiology laboratory must be notified before submission of any cultures from specimens that might contain tularemia, as they must observe special precautions to work with such samples due to risk of inhalation and subsequent severe pneumonia. We recommend discussion with an infectious diseases consultant for cases of suspected or proven tularemia.⁵

What about Lyme Disease?

The incidence of Lyme disease in Kansas and Missouri is low. Lyme disease is typically caused by the bacterium Borrelia burgdorferi and is spread to humans through the blacklegged deer (Ixodes spp.) tick. Typical symptoms of Lyme disease include fever, headache, fatigue and the characteristic erythema migrans rash. This rash occurs in 70%-80% of infected individuals. It starts at the site of the tick bite and develops on average seven days after the bite (range three to 30 days). The rash expands over several days, is rarely painful or itchy, and is round or oval, often uniform, but sometimes with a classic bull’s-eye appearance.^7,8 Untreated Lyme disease can progress to cause disseminated disease, including facial nerve palsy, heart block, meningitis and late manifestations such as arthritis.⁹ Children with classic erythema migrans rash after being in an area where Lyme disease is common do not need testing and can be treated empirically. Treatment for this early localized disease is doxycycline, amoxicillin or cefuroxime. For later stages of Lyme disease or a less straightforward presentation, testing and alternative treatment may be necessary. Tables and resources on testing and treatment are included in the clinical pathway. Highly consider consulting an infectious diseases physician when in doubt.⁵  

It’s important to mention Southern tick-associated rash illness (STARI), which has a rash similar in appearance to erythema migrans and presents with other symptoms like those of early Lyme disease. It is spread by the lone star tick and can occur even in regions where Lyme disease is low in prevalence or absent. It has no known sequelae but is often treated with amoxicillin or doxycycline.

Is Prophylaxis Indicated in a Child with a Tick Bite?

Antibiotic prophylaxis post-tick bite is not routinely recommended. Patients with a tick bite should be given anticipatory guidance and should seek care for fever, rash or other symptoms developing within two weeks of the tick bite. Prophylaxis for Lyme disease is recommended only when there is certainty of a high-risk bite and should be started within 72 hours. A high-risk bite is considered a bite that occurred in a highly endemic area (Kansas and Missouri are not in this category) where the tick was attached for >36 hours, and the tick was identified as a black legged/Ixodes spp. tick. In these cases, a single dose of oral doxycycline 4.4 mg/kg (maximum dose of 200 mg) can be given.⁵

References:

1. Preventing tick bites. Ticks. Centers for Disease Control and Prevention. Published May 17, 2024. Accessed April 29, 2025. https://www.cdc.gov/ticks/prevention/index.html
2. Tickborne disease. Missouri Department of Health & Senior Services. health.mo.gov. Accessed April 29, 2025. https://health.mo.gov/living/healthcondiseases/communicable/tickscarrydisease/index.php
3. About Rocky Mountain spotted fever. Rocky Mountain Spotted Fever (RMSF). Centers for Disease Control and Prevention. Published May 14, 2024. Accessed April 22, 2025. https://www.cdc.gov/rocky-mountain-spotted-fever/about/index.html
4. About ehrlichiosis. Ehrlichiosis. Centers for Disease Control and Prevention. Published May 20, 2024. Accessed April 22, 2025. https://www.cdc.gov/ehrlichiosis/about/index.html
5. Tickborne illness. Clinical Pathways. Children’s Mercy Kansas City. Accessed May 14, 2025. childrensmercy.org/health-care-providers/evidence-based-practice/cpgs-cpms-and-eras-pathways/tickborne-illness/
6. About tularemia. Tularemia. Centers for Disease Control and Prevention. Published May 1, 2024. Accessed April 22, 2025. https://www.cdc.gov/tularemia/about/index.html
7. About Lyme disease. Lyme Disease. Centers for Disease Control and Prevention. Published May 14, 2024. Accessed April 22, 2025. https://www.cdc.gov/lyme/about/index.html
8. Lyme disease rashes. Lyme Disease. Centers for Disease Control and Prevention. Published May 20, 2024. Accessed April 22, 2025. https://www.cdc.gov/lyme/signs-symptoms/lyme-disease-rashes.html
9. Signs and symptoms of untreated Lyme disease. Lyme Disease. Centers for Disease Control and Prevention. Published May 15, 2024. Accessed April 22, 2025. https://www.cdc.gov/lyme/signs-symptoms/index.html
10.