Scrub Typhus Management
First-Line Treatment
Doxycycline is the drug of choice for scrub typhus treatment in all patients, including children under 8 years of age, and should be initiated immediately when scrub typhus is suspected based on clinical presentation. 1
Adult Dosing
- Doxycycline 100 mg twice daily (oral or intravenous) 2, 1, 3
- Continue for at least 3 days after fever subsides with evidence of clinical improvement 2, 1
- Minimum total treatment course: 5-7 days 2, 1
- Severe or complicated disease may require longer courses 2, 1
Pediatric Dosing
- Children <45 kg: Doxycycline 2.2 mg/kg body weight twice daily (oral or intravenous) 2, 1
- Children ≥45 kg: Use adult dosing (100 mg twice daily) 1
- Loading dose option: 4.4 mg/kg as single dose, then 2.2 mg/kg every 12 hours 1
Route of Administration
- Intravenous therapy is indicated for hospitalized patients, particularly those who are vomiting or obtunded 2
- Oral therapy is acceptable for early disease managed outpatient or stable inpatients 2
Expected Clinical Response
Fever typically subsides within 24-48 hours after initiating doxycycline when treatment is started during the first 4-5 days of illness. 2, 1, 4
- Lack of response within 48 hours should prompt consideration of alternative diagnoses 2, 1
- Severely ill patients may require longer periods before clinical improvement, especially with multiple organ dysfunction 2
Alternative Treatments
Azithromycin
- Preferred alternative for pregnant women and children when doxycycline is contraindicated 5, 6
- Single 500 mg dose has shown equivalent efficacy to 7-day doxycycline course in mild scrub typhus 7
- Successfully used in pregnancy without relapse and with favorable outcomes 5
Chloramphenicol
- Dosing: 12.5-25 mg/kg every 6 hours IV (maximum 1 g/dose) 1
- The lower end of dosing range (12.5 mg/kg every 6 hours) is sufficient for most cases 1
- Serum concentration monitoring should be performed when available 1
Rifampin
- Dosing: 600 mg once daily for 5 days 8
- Effective in areas where doxycycline resistance is documented 6, 8
- Shown equivalent efficacy and safety compared to doxycycline in randomized controlled trial 8
Critical Clinical Considerations
Timing of Treatment
Treatment must be initiated immediately based on clinical suspicion and should never be delayed while awaiting laboratory confirmation. 1
- Delay in treatment can lead to severe disease, long-term sequelae, or death 2, 1
- Early use of doxycycline significantly reduces complications and mortality 4
- Patients who received anti-scrub antibiotics prior to hospitalization had fewer and milder complications with zero mortality compared to 6.6% mortality in untreated patients 4
Dental Staining Concerns in Children
The historical concern about dental staining in children under 8 years should not prevent the use of doxycycline for short courses of treatment. 1
- Limited use of tetracyclines during the first 6-7 years of life has negligible effect on permanent tooth color 2
- Multiple exposures increase risk, but short courses for life-threatening infections like scrub typhus do not pose substantial risk 2
- The American Academy of Pediatrics identifies doxycycline as the drug of choice for treating rickettsial diseases in children 2
Common Pitfalls to Avoid
Dosing Errors in Children
- Always calculate dose based on actual body weight, not age alone 1
- Verify syrup concentration before calculating mL doses to avoid underdosing 1
- For 25 mg/5 mL suspension: multiply total mg dose by 0.2 1
- For 50 mg/5 mL suspension: multiply total mg dose by 0.1 1
Delayed Diagnosis
- Scrub typhus should be included in initial empirical antimicrobial therapy for febrile patients during tick season in endemic areas 4
- Average duration of illness before presentation in fatal cases was 9.2 days, emphasizing the importance of early treatment 4