Treatment of Suspected Tick-Borne Illness
Doxycycline is the drug of choice for treatment of all suspected tick-borne rickettsial diseases in patients of all ages, including children under 8 years, and should be initiated immediately without waiting for laboratory confirmation. 1, 2
Initial Assessment and Treatment
First-line Treatment
- Adults: Doxycycline 100 mg twice daily (orally or intravenously) 1, 3
- Children <45 kg: Doxycycline 2.2 mg/kg body weight twice daily (orally or intravenously) 1, 2
- Duration: At least 5-7 days and at least 3 days after fever subsides 1
- Route:
- Oral therapy for early/mild disease in outpatients
- IV therapy for hospitalized patients, especially those who are severely ill, vomiting, or obtunded 1
Critical Timing
- Treatment should be initiated immediately upon suspicion of a tick-borne illness
- Delay in treatment can lead to severe disease, long-term sequelae, or death 1
- Do not wait for laboratory confirmation before starting treatment 1, 2
Specific Tick-Borne Diseases and Treatment Considerations
Rocky Mountain Spotted Fever (RMSF)
- Doxycycline is the only recommended treatment
- Chloramphenicol is an alternative but is demonstrably inferior to doxycycline 4
- RMSF has a higher mortality rate than other tick-borne diseases 5
Ehrlichiosis and Anaplasmosis
- Doxycycline is the treatment of choice 1
- For anaplasmosis only: Rifampin (300 mg twice daily for adults or 10 mg/kg for children) may be considered as an alternative in cases of pregnancy or documented allergy to tetracycline-class drugs 1
- Treatment should be extended to 10 days if concurrent Lyme disease is suspected 1
Special Populations
Children
- Doxycycline is the drug of choice for all ages, including children under 8 years 1, 2
- Previous concerns about tooth staining in children have been disproven by recent studies 1
- Short courses of doxycycline (used at recommended doses) do not cause tooth staining or enamel hypoplasia 1
Pregnancy
- While tetracyclines are generally contraindicated during pregnancy, doxycycline may be warranted in life-threatening situations where clinical suspicion of tick-borne rickettsial disease is high 1
Doxycycline Allergy
- For non-life-threatening reactions: Consider administering doxycycline in an observed setting 1
- For life-threatening tetracycline allergy: Consider alternative agents or rapid doxycycline desensitization in consultation with an allergy specialist 1
Hospitalization Criteria
Consider hospitalization for patients with:
- Evidence of organ dysfunction
- Severe thrombocytopenia
- Mental status changes
- Need for supportive therapy 1, 2
Important Cautions
Ineffective Treatments
The following antibiotics are NOT effective against tick-borne rickettsial diseases:
- Beta-lactams
- Macrolides
- Aminoglycosides
- Sulfonamides (may actually increase disease severity)
- Fluoroquinolones 1, 2
Monitoring Response
- Improvement typically occurs within 24-48 hours after treatment initiation 2
- Lack of improvement within 48 hours suggests alternative diagnosis or coinfection 1
- Close follow-up is essential for patients treated as outpatients 1
Prophylaxis
- Prophylactic antibiotics after tick bites in asymptomatic individuals are not recommended 1, 2
- The most effective preventive measures include limiting exposure to ticks, thorough body inspection after outdoor activities, prompt removal of attached ticks, and use of insect repellents 1
Common Pitfalls to Avoid
- Delaying treatment while awaiting laboratory confirmation
- Assuming a rash must be present (rash is rare in anaplasmosis)
- Using ineffective antibiotics, particularly sulfonamides which may worsen disease
- Withholding doxycycline from children under 8 years due to outdated concerns about tooth staining
- Failing to consider coinfection when response to treatment is inadequate 1, 2