What are the characteristics and treatment of typhus fever?

Typhus Fever Characteristics and Treatment

Typhus fever is characterized by fever, headache, and rash, with treatment primarily consisting of doxycycline as the first-line antibiotic therapy for all forms of typhus. 1

Types and Epidemiology

Typhus fever refers to several related rickettsial diseases that can be categorized into three main types:

1. Murine typhus (endemic typhus)

   • Caused by: Rickettsia typhi
   • Transmission: Rat fleas (Xenopsylla cheopis)
   • Distribution: Found throughout tropical and subtropical areas, particularly in port cities and coastal regions with dense rodent populations 2
   • Mortality: Up to 4% if untreated 2

2. Epidemic typhus

   • Caused by: Rickettsia prowazekii
   • Transmission: Human body lice
   • Distribution: Areas with poor sanitation and crowded conditions

3. Scrub typhus

   • Caused by: Orientia tsutsugamushi
   • Transmission: Mite bites
   • Distribution: Rural areas of South Asia, Southeast Asia, and Western Pacific 2
   • Mortality: Up to 32% if untreated 2

Clinical Presentation

Common Symptoms and Signs

• Fever (present in >80% of cases) 2
• Headache (present in >80% of cases) 2
• Myalgia (muscle pain) 2
• Maculopapular rash (present in <50% of cases) 2, 3
• Inoculation eschar (seen in <50% of cases, particularly with scrub typhus) 2
• Regional lymphadenitis (seen in <50% of cases) 2

Specific Presentations by Type

Murine Typhus:

• Generally milder disease 2
• Night fevers may be the only presenting symptom in some patients 4
• Slightly enlarged liver and skin rash may be the only significant physical signs 4
• Can present with gastrointestinal symptoms including nausea and diarrhea 3

Scrub Typhus:

• Often presents with fever, tachypnea, and hepatosplenomegaly 4
• Skin rash is less common than in other forms 4
• Eschar may be absent in many cases 4

Laboratory Findings

• Leukopenia (decreased white blood cell count) 5, 3
• Thrombocytopenia (decreased platelet count) 5, 3
• Elevated inflammatory markers (CRP, procalcitonin) 3
• Elevated liver enzymes 5
• In severe cases: evidence of renal dysfunction 5

Complications

While most cases are mild, complications can occur, particularly with Mediterranean spotted fever, murine typhus, and scrub typhus 2:

• Liver failure 5
• Renal failure requiring hemodialysis 5
• Pneumonia 3, 4
• Meningitis 4
• Reactive arthritis (particularly with African tick bite fever) 2

Diagnosis

1. Clinical suspicion based on:

   • Travel history to endemic areas
   • Characteristic triad of fever, headache, and rash
   • Exposure to potential vectors (fleas, mites)

2. Serological testing:

   • Specific IgM and IgG antibodies against Rickettsia typhi or other rickettsial species 6, 3
   • Significant increase in antibody titers in paired samples is diagnostic 3

3. PCR for rickettsial DNA in blood or tissue samples

Treatment

First-line Treatment

Doxycycline is the drug of choice for all forms of typhus 1:

• Adult dosage: 100 mg twice daily for 7-14 days
• Pediatric dosage: 2.2 mg/kg twice daily (maximum 100 mg per dose)
• Treatment should be initiated based on clinical suspicion without waiting for laboratory confirmation 2

Alternative Treatments

• Fluoroquinolones (such as ciprofloxacin) may be used as alternative therapy 2, 7
• Azithromycin can be considered in patients with contraindications to doxycycline 2

Response to Treatment

• Clinical improvement typically occurs within 24-48 hours of appropriate antibiotic therapy 2
• If no improvement is seen within this timeframe, alternative diagnoses should be considered 2

Prognosis

• With appropriate and timely treatment, the prognosis is excellent with cure rates approaching 100% 8
• Even without specific treatment, many cases of murine typhus are self-limiting, though treatment significantly reduces duration and severity 8
• The mean duration of fever is approximately 12.5 days 8

Prevention

• Vector control (flea, louse, and mite control)
• Rodent control in endemic areas
• Use of insect repellents and protective clothing in endemic areas
• Prompt treatment of identified cases

Important Clinical Considerations

• Typhus can be misdiagnosed as enteric fever (typhoid) due to similar presentations 4
• A high index of suspicion is needed in patients with fever, headache, and rash returning from endemic areas 3
• Treatment should not be delayed while awaiting laboratory confirmation if typhus is suspected 2
• Severe complications, while uncommon (8.6%), can be life-threatening if treatment is delayed 8