What is the recommended treatment for scrub typhus?

Recommended Treatment for Scrub Typhus

Doxycycline is the drug of choice for treating scrub typhus in all patients, including children under 8 years of age, and should be started immediately when scrub typhus is suspected—never delay treatment while awaiting laboratory confirmation. 1, 2

First-Line Treatment Regimen

Adult Dosing

• Doxycycline 100 mg twice daily (oral or intravenous) 1, 2
• Continue for at least 3 days after fever subsides 1, 2
• Minimum total treatment course: 5-7 days 1, 2

Pediatric Dosing

• Children under 45 kg: Doxycycline 2.2 mg/kg body weight twice daily (oral or intravenous) 1, 2
• Children 45 kg or above: Use adult dosing (100 mg twice daily) 2
• Loading dose option: 4.4 mg/kg as a single dose, then 2.2 mg/kg every 12 hours 1

Route Selection

• Intravenous therapy is indicated for hospitalized patients 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 1, 2
• Lack of response within 48 hours should prompt consideration of alternative diagnoses 1, 2
• This rapid response is a hallmark of appropriate treatment and helps confirm the diagnosis 1

Alternative Treatment Options

Chloramphenicol

• Dose: 12.5-25 mg/kg every 6 hours IV 1
• Can be used as an alternative agent when doxycycline is contraindicated 1

Azithromycin

• A single 500-mg dose of azithromycin showed equivalent efficacy to a 1-week course of doxycycline in mild scrub typhus, with median time to defervescence of 21 hours versus 29 hours 3
• May be considered for pregnancy or when doxycycline is contraindicated 4

Rifampin

• Dose: 600-900 mg once daily for 5 days 5, 6
• In northern Thailand, rifampin demonstrated superior efficacy to doxycycline (fever clearance time 22.5-27.5 hours vs 52 hours) in areas with reduced antibiotic susceptibility 6
• May be considered as an alternative treatment, particularly in regions with documented doxycycline resistance 5, 6

Critical Clinical Considerations

Timing is Everything

• Treatment must be initiated immediately based on clinical suspicion 1, 2
• Delay in treatment can lead to severe disease, long-term sequelae, or death 1, 2
• Mortality rates up to 4% have been reported when treatment is delayed 1

Pediatric Safety

• The historical concern about dental staining in children under 8 years should not prevent the use of doxycycline for short courses 1, 2
• Limited use of tetracyclines during the first 6-7 years of life has negligible effect on permanent tooth color 2
• The CDC and American Academy of Pediatrics both endorse doxycycline as first-line treatment in children of all ages for rickettsial diseases 1, 2

Common Pitfalls to Avoid

Dosing Errors

• Always calculate dose based on actual body weight, not age alone 1, 2
• Verify syrup concentration before calculating mL doses to avoid underdosing 1, 2
• For liquid formulations: multiply total mg dose by 0.2 if using 25 mg/5 mL suspension, or by 0.1 if using 50 mg/5 mL suspension 1

Premature Discontinuation

• Do not discontinue treatment prematurely—continue for at least 3 days after fever resolution 1, 2
• Ensure minimum 5-7 day total course is completed 1, 2
• Severe or complicated disease may require longer treatment courses 1

Delayed Treatment

• Early clinical suspicion and early use of doxycycline reduces scrub typhus-associated complications 4
• Patients who received anti-scrub antibiotics prior to admission had fewer and milder complications with no mortality, compared to those presenting late (average 9.2 days) without prior treatment 4