Causes:
- Caused by the bacterium Orientia tsutsugamushi, transmitted via the bite of infected chiggers (larval mites).
- Common in rural areas with heavy vegetation, particularly in Southeast Asia and the western Pacific.
- Signs and Symptoms:
- Incubation period: 1–3 weeks.
- Early symptoms:
- Malaise, chills, severe headache, backache.
- High fever (often ≥39°C), relative bradycardia (heart rate does not increase proportionally with fever).
- Eschar: A black, necrotic lesion at the bite site (commonly in the groin, abdomen, chest, or axilla).
- Later symptoms:
- Rash (maculopapular, may appear on trunk, limbs, or face; fleeting or persistent).
- Organ involvement: Hepatosplenomegaly, pneumonia, meningitis, or renal failure in severe cases.
- Diagnosis:
- Clinical suspicion + eschar presence.
- Lab tests: CBC (leukopenia, thrombocytopenia), liver/kidney function tests, serology (Weil-Felix test, ELISA, PCR).
- Treatment:
- First-line: Doxycycline (100 mg twice daily for 7–10 days) or azithromycin (500 mg once daily for 5 days) if doxycycline contraindicated.
- Rationale: Doxycycline is highly effective against O. tsutsugamushi and shortens illness duration.
- Supportive care: Hydration, antipyretics, and monitoring for complications (e.g., ARDS, shock).
- Prevention:
- Avoid chigger-infested areas; wear protective clothing; use insect repellents (DEET, permethrin).
Note: Early treatment is critical to prevent severe complications. If symptoms persist, seek medical evaluation for confirmatory tests.