Common Causes of Fever with Rash in Thailand:
- Dengue fever: High fever, severe headache, pain behind the eyes, muscle and joint pain, and a characteristic rash (flushing, petechiae, or maculopapular rash).
Rationale: Dengue is endemic in Thailand, and the rash often appears 3–4 days after fever onset.
- Chikungunya: Sudden fever, severe joint pain, and a maculopapular rash (often on the trunk and limbs).
Rationale: Chikungunya is also prevalent in Thailand, and the rash typically appears within the first 2 days of fever.
- Scrub typhus: High fever, rash (maculopapular, often on the trunk), and eschar (black scab) at the bite site.
Rationale: Scrub typhus is common in rural areas, transmitted by mites.
- Drug reactions (e.g., DRESS, AGEP): Fever, widespread rash, and systemic symptoms (lymphadenopathy, organ involvement).
Rationale: Common in patients on antibiotics or anticonvulsants.
- Meningococcal disease: Sudden fever, petechial/purpuric rash, and signs of meningitis (neck stiffness, altered consciousness).
Rationale: Rare but life-threatening; requires urgent treatment.
- Initial Approach:
- History: Travel, drug exposure, contact with animals, recent illnesses.
- Examination: Check for eschar (scrub typhus), petechiae (meningococcal), or joint pain (chikungunya).
- Investigations:
- Complete blood count (CBC), liver function tests (LFTs), and blood cultures.
- Dengue and chikungunya serology/PCR if available.
- Consider scrub typhus serology if rural exposure.
- If meningococcal is suspected, start empirical antibiotics (e.g., ceftriaxone) immediately.
- Key Considerations:
- Dengue vs. chikungunya: Dengue has more severe muscle/joint pain; chikungunya has more persistent joint pain.
- Scrub typhus: Look for eschar (often missed if small).
- Drug reactions: Stop the suspected drug and monitor for progression.
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