Scrub Typhus: Treatment and Management
Immediate Treatment Recommendation
Doxycycline is the drug of choice for scrub typhus and must be initiated immediately upon clinical suspicion—do not delay treatment while awaiting laboratory confirmation, as treatment delay is associated with mortality rates up to 4%. 1, 2
First-Line Antibiotic Therapy
Doxycycline Dosing
Adults:
- 100 mg twice daily (oral or intravenous) 1, 2
- Continue for at least 3 days after fever subsides 2
- Minimum treatment course: 5-7 days 3, 2
Children (all ages, including <8 years):
- 2.2 mg/kg body weight twice daily (oral or intravenous) for children <45 kg 1, 2
- 100 mg twice daily for children ≥45 kg 2
- The historical concern about dental staining should NOT prevent doxycycline use in children under 8 years for short treatment courses 2
Route of Administration
- Oral therapy is acceptable for outpatients early in disease who are not vomiting 3
- Intravenous therapy is indicated for hospitalized patients, particularly those with multi-organ dysfunction, vomiting, or altered mental status 2
Expected Clinical Response
Fever typically subsides within 24-48 hours after initiating doxycycline in early disease. 1, 2
Critical decision point: If fever persists beyond 48 hours after starting doxycycline, strongly reconsider the diagnosis and evaluate for alternative or co-infecting pathogens (malaria, dengue, enteric fever, leptospirosis). 1
Exception: Severely ill patients with multi-organ dysfunction may require >48 hours before clinical improvement is noted. 1, 2
Alternative Antibiotic Options
Chloramphenicol
- Dose: 12.5-25 mg/kg every 6 hours intravenously 1, 2
- Use as alternative when doxycycline is contraindicated 4
Azithromycin
- Can be used for mild scrub typhus, though evidence is limited 1
- Preferred agent in pregnancy: Azithromycin has been used successfully in pregnant women without relapse and with favorable pregnancy outcomes 4
Hospitalization Criteria
Hospitalize patients with any of the following: 3
- Evidence of organ dysfunction
- Severe thrombocytopenia
- Mental status changes
- Need for supportive therapy
- Inability to tolerate oral medications
At least 50% of scrub typhus patients require hospitalization. 3
Clinical Presentation to Recognize
Cardinal Features
- Fever: Most consistent symptom, beginning 6-10 days after chigger bite 1
- Eschar: Painless necrotic lesion with black crust surrounded by erythema at bite site—present in only 60% of cases 1
- Headache, myalgia, malaise: Common accompanying symptoms 1
Gastrointestinal and Respiratory Manifestations
- Nausea, vomiting, diarrhea, abdominal pain occur frequently 1
- Pneumonia develops in up to 36% of cases 3, 1
- ARDS occurs in 15% of untreated cases 3, 1
Laboratory Abnormalities
- Leukopenia, thrombocytopenia, mild hyponatremia 3
- Mildly elevated hepatic transaminases 3
- Absence of these findings does NOT exclude scrub typhus 3
Severe Disease and Complications
Multi-Organ Dysfunction Management
For patients with multi-organ failure: 2
- Use intravenous doxycycline
- Severe or complicated disease requires longer treatment courses (beyond the standard 5-7 days)
- Careful fluid management is essential—avoid overhydration as pulmonary complications occur in up to 36% of cases 1
Specific Organ Complications
- CNS involvement (meningitis/meningoencephalitis): Present in ~20% of patients 1
- Acute renal failure: Occurs in 9% of cases, may require renal replacement therapy 1
- Respiratory failure: Leading cause of death in severe cases 5
High-Risk Populations
- Children <10 years have higher mortality risk if treatment is delayed 1
- Pregnant women face increased fetal loss, preterm delivery, and small-for-gestational-age infants 4
Diagnostic Approach
When to Suspect Scrub Typhus
- Fever with headache, myalgia in endemic areas (South Asia, Southeast Asia, Western Pacific) 1, 6
- History of outdoor activities in rural/grassy areas, especially April-September 6
- Absence of tick bite history does NOT exclude diagnosis—up to 40% report no bite 3
Laboratory Testing
- Serological testing is primary diagnostic method, but treatment must NEVER be delayed awaiting results 1
- Paired serum samples 2-4 weeks apart showing ≥4-fold antibody rise confirms diagnosis 1
- Blood cultures should be obtained before therapy when possible 1
Prevention Strategies
Personal Protective Measures
- Wear long-sleeved shirts, long pants tucked into boots during outdoor activities 6
- Apply DEET-based repellent (10-30% concentration) to exposed skin 3, 6
- Treat clothing with permethrin 3, 6
- Avoid sitting or lying directly on ground in endemic areas 6
Post-Exposure Actions
- Inspect body thoroughly for mites after outdoor exposure—scalp, axillae, groin, waistline 3
- Remove attached mites immediately with tweezers close to skin 3
- Do NOT use folk remedies (gasoline, petroleum jelly, matches) 3
Critical Pitfalls to Avoid
- Never delay treatment awaiting laboratory confirmation—mortality increases significantly with delayed therapy 1, 2
- Do not withhold doxycycline from children <8 years—short courses do not cause clinically significant dental staining 2
- Do not dismiss diagnosis based on absence of eschar—present in only 60% of cases 1
- Do not assume treatment failure if fever persists <48 hours in severely ill patients—multi-organ dysfunction requires longer response time 1, 2
- Always calculate pediatric doses by actual body weight, not age alone 2