## Scrub Typhus Treatment — First-Line Agent **Key Point:** Doxycycline is the gold-standard first-line treatment for scrub typhus (Orientia tsutsugamushi infection) in adults and children ≥8 years. ### Mechanism & Dosing - **Drug class:** Tetracycline (protein synthesis inhibitor) - **Standard dose:** 100 mg orally twice daily for 7–14 days - **Onset:** Rapid defervescence within 24–48 hours of initiation - **Efficacy:** >95% cure rate when given early ### Why Doxycycline is Preferred | Feature | Doxycycline | Chloramphenicol | Fluoroquinolone | Macrolide | |---------|-------------|-----------------|-----------------|----------| | **First-line status** | Yes | No (2nd-line) | No | No | | **Bioavailability** | Excellent oral | Good | Good | Moderate | | **CNS penetration** | Moderate | Excellent | Moderate | Poor | | **Cost** | Low | Moderate | Moderate | Low | | **Resistance** | Rare | Rare | Emerging | Rare | | **Safety in pregnancy** | Contraindicated | Relative CI | Relative CI | Safe | **High-Yield:** Doxycycline is the **preferred agent in endemic areas** (India, Southeast Asia, Pacific) because of rapid clinical response, oral bioavailability, and low cost. ### Alternative Regimens - **Chloramphenicol 50 mg/kg/day** — reserved for pregnant women or doxycycline allergy; slower response - **Azithromycin 500 mg daily** — emerging role in pregnancy; less robust data than doxycycline - **Fluoroquinolones** — not recommended as monotherapy; inferior to tetracyclines **Clinical Pearl:** Delayed or inadequate treatment increases risk of complications (myocarditis, ARDS, DIC), particularly in severe scrub typhus. **Tip:** In NEET PG, when you see "eschar + fever + endemic area," immediately think **doxycycline**. The eschar (tache noire) is pathognomonic for scrub typhus. [cite:Harrison 21e Ch 187]
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