What are the symptoms and treatment of scrub typhus?

Scrub Typhus: Symptoms and Treatment

Scrub typhus presents with fever, headache, and malaise, often accompanied by an eschar at the site of the mite bite, and requires prompt treatment with doxycycline to prevent potentially fatal complications. 1, 2

Clinical Manifestations

Primary Symptoms

• Fever: Present in nearly 100% of cases 3, 4
• Headache: Common and can be severe 1, 2
• Malaise and myalgia: Frequently reported 2, 4
• Eschar: Present in approximately 60% of cases - a black necrotic lesion at the site of the mite bite 3, 5
• Lymphadenopathy: Occurs in about 33% of patients 3
• Rash: Maculopapular rash appears in approximately 21% of cases 3, 4

Respiratory Symptoms

• Cough (24% of cases) 3
• Dyspnea (18% of cases) 3

Gastrointestinal Symptoms

• Diarrhea (18% of cases) 3
• Nausea and vomiting 2, 4

Laboratory Abnormalities

• Leukopenia (19% of cases) 3
• Leukocytosis (34% of cases) 3
• Thrombocytopenia (44% of cases) 3
• Elevated liver enzymes (AST and ALT) in 75-81% of cases 3

Serious Complications

Scrub typhus can progress to life-threatening complications if not treated promptly:

• Pneumonitis: Occurs in 36% of cases 3
• Acute Respiratory Distress Syndrome (ARDS): Seen in 15% of cases 3, 6
• Acute renal failure: Develops in 9% of cases 3
• Myocarditis: Reported in 3% of cases 3
• Septic shock: Occurs in 3% of cases 3
• Hemophagocytic lymphohistiocytosis: Rare but severe complication 6
• Neurological complications: Including meningoencephalitis and seizures 2, 6
• Multi-organ dysfunction syndrome: Can develop in severe cases 7

Diagnostic Approach

Clinical Diagnosis

• Look for the characteristic triad of fever, rash, and eschar 5
• Be aware that not all patients will present with the complete triad 5
• Perform thorough skin examination to identify eschar, which may be in hidden areas 5

Laboratory Diagnosis

• Early disease (<7 days): Quantitative PCR is most sensitive 7
• Later disease: IgM ELISA and rapid diagnostic tests show excellent sensitivity and specificity 7
• Consider scrub typhus in patients with unexplained fever, respiratory symptoms, and elevated liver enzymes, especially in endemic areas 3, 5

Treatment

First-line Treatment

• Doxycycline: The drug of choice for all ages 2, 8
  • Adults: 100 mg every 12 hours orally or intravenously 2, 8
  • Children <45 kg: 2.2 mg/kg every 12 hours (maximum 100 mg per dose) 2
  • Duration: Minimum 5-7 days or until 48-72 hours after the patient becomes afebrile 2

Alternative Treatment

• Azithromycin: Alternative for those who cannot take doxycycline 7

Treatment Response

• Patients typically respond within 24-48 hours of antibiotic initiation 1
• If no response occurs within this timeframe, consider alternative diagnoses 1

Management of Severe Cases

• Intensive supportive care for complications like ARDS, renal failure, or shock 3, 6
• Early recognition and prompt treatment are crucial to prevent mortality 3, 6

Clinical Pitfalls to Avoid

1. Delayed diagnosis: Scrub typhus can be fatal if treatment is delayed; maintain high clinical suspicion in endemic areas 3, 5
2. Overlooking eschar: Perform thorough skin examination as eschar may be in hidden locations 5
3. Misdiagnosis: Symptoms may mimic other infections like infectious mononucleosis or viral hepatitis 5
4. Waiting for laboratory confirmation: Treatment should be initiated based on clinical suspicion in endemic areas 2
5. Underestimating severity: Be vigilant for signs of rapid deterioration, especially respiratory distress 3, 6

Scrub typhus is an important consideration in febrile patients from endemic regions in Asia-Pacific, particularly rural South and Southeast Asia. Early recognition and prompt treatment with appropriate antibiotics are essential to prevent potentially fatal complications.