Treatment of Scrub Typhus
Doxycycline is the drug of choice for treating scrub typhus in patients of all ages, including children under 8 years, and should be initiated immediately when scrub typhus is suspected. 1
First-Line Treatment Regimen
- For adults: Doxycycline 100 mg twice daily (orally or intravenously) for at least 3 days after fever subsides, with a minimum treatment course of 5-7 days 1
- For children under 45 kg: Doxycycline 2.2 mg/kg body weight twice daily (orally or intravenously) 1
- Treatment should never be delayed while awaiting laboratory confirmation, as delays can lead to severe disease, long-term sequelae, or death 1
- Patients typically respond to appropriate antibiotics within 24-48 hours; lack of response within this timeframe should prompt consideration of alternative diagnoses 1
Alternative Treatment Options
- Azithromycin (500 mg single dose) has shown equivalent efficacy to doxycycline in treating mild scrub typhus 2
- Azithromycin is the recommended treatment for pregnant women and can be used successfully without relapse and with favorable pregnancy outcomes 3
- Rifampin (600 mg once daily for 5 days) may be considered an alternative treatment to doxycycline with equivalent treatment effects and safety profile 4
- Rifampin is particularly effective in areas where doxycycline-resistant strains have been reported 5
Clinical Considerations
- The historical concern about dental staining in children under 8 years should not prevent the use of doxycycline for short courses of treatment 1
- Scrub typhus is caused by Orientia tsutsugamushi, transmitted by the bites of infected mites (chiggers) 1
- Clinical manifestations include fever, headache, myalgia, and sometimes an eschar (a necrotic lesion with a black crust) at the site of the chigger bite 1
- Laboratory findings may include leukopenia, thrombocytopenia, and deranged hepatic and renal function 3
Treatment Response and Follow-up
- Continue treatment for at least 3 days after fever subsides 1
- Severe or complicated disease may require longer treatment courses 1
- Weekly doxycycline (200 mg) has shown 89% efficacy as prophylaxis in high-risk exposure settings, though this is not routinely recommended 6
- No relapses have been reported with appropriate treatment courses of doxycycline or azithromycin 2
Cautions and Pitfalls
- Single-dose doxycycline treatment has been associated with relapses and is not recommended 6
- Doxycycline-resistant strains have been reported in parts of northern Thailand, necessitating alternative treatments like rifampin in these regions 5
- Mortality rates of up to 4% have been reported in untreated or inadequately treated cases 1
- Quinolones have shown some efficacy but evidence is limited, and they should not be first-line therapy 5