What are the symptoms and treatment of scrub typhus?

Scrub Typhus Symptoms and Treatment

Scrub typhus typically presents with sudden onset of fever, severe headache, general malaise, and myalgias, with an eschar present in only about 33% of patients, and should be treated with doxycycline as the first-line therapy. 1

Clinical Presentation

Scrub typhus has a characteristic presentation with several key symptoms:

• Initial symptoms (6-21 days after mite bite):

  • Sudden onset of fever
  • Severe headache
  • General malaise
  • Myalgias 1

• Characteristic skin findings:

  • Eschar (present in only about 33% of patients)
  • Maculopapular rash that may become petechial, typically appearing 2-4 days after fever onset 1

• Other common symptoms include:

  • Chills (23.8%)
  • Cough (18.3%)
  • Headache (14.3%) 2
  • Nausea 3

The disease can manifest with four possible overlapping clinical presentations:

1. Mild disease
2. Respiratory predominant disease
3. Central nervous system predominant disease (meningoencephalitis)
4. Sepsis syndrome 4

Diagnosis

Clinical suspicion is crucial in endemic areas for diagnosing scrub typhus. The diagnosis can be confirmed through:

• Clinical findings (especially the presence of eschar)
• Serology (indirect immunofluorescence to detect IgM and IgG)
• PCR (most sensitive in early disease, <7 days)
• IgM ELISA and rapid diagnostic tests (excellent sensitivity and specificity in later disease) 1

Treatment

First-line treatment:

• Doxycycline is the treatment of choice for scrub typhus
  • Adults: 100 mg every 12 hours orally or intravenously
  • Children <45 kg: 2.2 mg/kg every 12 hours (maximum 100 mg per dose) 1, 5

Important treatment considerations:

• Early empiric treatment with doxycycline, initiated within the first 5 days of illness, significantly reduces mortality
• Treatment should not be delayed pending laboratory confirmation or rash development 1
• For pregnant women, azithromycin is recommended instead of doxycycline 1

Complications

Without prompt treatment, scrub typhus can lead to severe complications:

• Acute respiratory distress syndrome (ARDS)
• Septic shock
• Multisystem organ failure
• Metabolic acidosis
• Altered sensorium
• Cardiac complications including atrial fibrillation 4, 6

Prognosis

• Good prognosis is expected with early diagnosis and appropriate treatment
• Mortality rate increases with delayed treatment
• Approximately 4% mortality due to multiorgan dysfunction can occur in untreated cases 1
• Independent predictors of mortality include metabolic acidosis, ARDS, altered sensorium, and shock 4

Prevention

Prevention strategies include:

• Avoiding areas infested with mites
• Using protective clothing (long sleeves, long pants)
• Applying DEET repellents
• Checking the body for attached mites after outdoor activities 1

Clinical Pearls and Pitfalls

• Pitfall: The characteristic eschar is absent in approximately 67% of patients, which can lead to missed diagnosis 1
• Pitfall: Symptoms can be nonspecific and may mimic other infectious diseases, including infectious mononucleosis 7
• Pearl: Systemic symptoms are most severe during the early stages of illness (first 5 days) but resolve slowly within 2 weeks 3
• Pearl: The dramatic therapeutic response to doxycycline can be both diagnostic and therapeutic 4