Scrub typhus is a rickettsial infection caused by the bacterium Orientia tsutsugamushi. It is spread through the bite of the larva (chigger) of trombiculid mites, which are commonly found in scrub vegetation. Key details include:

Exposure and Transmission:

• History of exposure to vegetation, such as working in fields or trekking, is crucial for acquiring the infection.

Incubation Period:

• Symptoms typically develop after 1-3 weeks of incubation.

Clinical Findings:

• Symptoms: Malaise, chills, severe headache, backache.
• Physical Signs: A papule at the bite site may evolve into a flat black eschar, commonly found in the groin, abdomen, chest, or axilla. This eschar is a vital clue for diagnosis.
• Rash: May appear on the trunk, lasting up to 21 days. Relative bradycardia (heart rate increase of fewer than 10 beats/min per degree Celsius rise in temperature) may be present.
• Gastrointestinal Symptoms: Often reported.

Investigations:

• Complete blood count (CBC), electrolytes, creatinine, urea, and liver function tests (LFT). Typical abnormalities include leukocytosis and thrombocytopenia.

Epidemiology:

• Scrub typhus is prevalent in regions with scrub vegetation and is a significant concern in many tropical and subtropical areas.

Treatment

• Doxycycline: The first-line treatment is doxycycline (100 mg orally twice daily) for at least 7 days. It is highly effective and well-tolerated.
• Alternative Options:
  • Azithromycin: 500 mg orally on the first day, followed by 250 mg daily for 4 days.
  • Chloramphenicol: 500 mg orally or intravenously every 6 hours for 7 days (used when doxycycline is contraindicated, such as in pregnant women or children under 8 years).
  • Minocycline or Rifampin: May also be considered in some cases.