What is the recommended treatment for scrub typhus?

Treatment of Scrub Typhus

Doxycycline is the first-line treatment for scrub typhus in patients of all ages, including children under 8 years, and should be initiated immediately upon clinical suspicion to prevent complications and death. 1, 2, 3

First-Line Treatment Options

Adults:

• Doxycycline: 200 mg loading dose, followed by 100 mg twice daily (orally or IV) for at least 3 days after fever subsides 1
  • Typical total treatment duration: 5-7 days
  • Expected response: Fever typically subsides within 24-48 hours of treatment initiation

Children:

• Doxycycline: 2.2 mg/kg body weight twice daily (orally or IV) for children weighing <45 kg 1
  • Maximum dose: 100 mg per dose
  • Same duration as adults: at least 3 days after fever subsides

Special Populations:

• Pregnant women and children <8 years: Azithromycin is preferred due to its safety profile 4
  • Single 500 mg dose of azithromycin has been shown to be as effective as a 1-week course of doxycycline for mild scrub typhus 5

Alternative Treatment Options

If doxycycline is unavailable or contraindicated:

• Azithromycin: Single 500 mg dose (for adults) 5, 4

  • Equally efficacious as doxycycline with fewer adverse effects
  • Particularly recommended for pregnant women and children

• Chloramphenicol: 12.5-25 mg/kg every 6 hours IV (maximum 1 g/dose) 1

  • Less commonly used today due to potential adverse effects

• Rifampicin: Consider in areas with documented doxycycline resistance (parts of northern Thailand) 4

Treatment Response and Monitoring

• Most patients (>90%) become afebrile within 72 hours after starting appropriate therapy 6
• If no clinical response within 48 hours of doxycycline treatment, consider:
  • Alternative diagnoses
  • Possible doxycycline resistance
  • Need for supportive care for complications

Clinical Pearls and Pitfalls

1. Early treatment is crucial: Delayed treatment significantly increases the risk of complications and mortality 3

   • In one study, all patients who died had not received anti-rickettsial antibiotics prior to hospitalization and presented late with an average illness duration of 9.2 days 3

2. Single-dose therapy: A single 200 mg dose of doxycycline has been shown to be as effective as a seven-day course of tetracycline in some studies, with no relapses observed 7

3. Diagnostic challenges: Treatment should never be delayed while awaiting laboratory confirmation, as early clinical suspicion and empiric treatment significantly reduce complications 1, 3

4. Route of administration: Oral therapy is appropriate for early-stage disease in outpatients, while IV therapy may be indicated for severely ill patients requiring hospitalization 1

5. Treatment failure: If fever persists beyond 48-72 hours after initiating doxycycline, reassess diagnosis and consider alternative or additional antimicrobial therapy 1

Conclusion

Prompt initiation of appropriate antibiotic therapy is the cornerstone of scrub typhus management. Doxycycline remains the drug of choice for most patients, with azithromycin as an excellent alternative, particularly for pregnant women and young children. Early clinical suspicion and treatment initiation are critical factors in preventing complications and reducing mortality.