Typhus
Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management
Definition
Typhus refers to a group of febrile illnesses caused by Rickettsia species, transmitted via arthropod vectors such as lice, fleas, and mites.
Aetiology
- Epidemic typhus: caused by Rickettsia prowazekii, transmitted by body lice.
- Endemic (murine) typhus: caused by Rickettsia typhi, transmitted by fleas.
- Scrub typhus: caused by Orientia tsutsugamushi, transmitted by mites (chiggers).
Pathophysiology
- Bacteria invade endothelial cells, leading to widespread vasculitis.
- Increased vascular permeability results in hypotension and multi-organ involvement.
Risk Factors
- Exposure to lice, fleas, or mites in endemic areas.
- Poor sanitation and overcrowded living conditions.
- Travel to endemic regions (South America, Africa, Southeast Asia).
Signs and Symptoms
- High fever with chills.
- Headache, myalgia, and malaise.
- Maculopapular rash spreading from trunk to extremities.
- Hepatosplenomegaly.
- Severe cases: neurological involvement (confusion, seizures), multi-organ failure.
Investigations
- Serology: detection of Rickettsia antibodies (IFA test).
- Polymerase chain reaction (PCR): confirms rickettsial DNA.
- Full blood count (FBC): may show leukopenia or thrombocytopenia.
- Liver function tests (LFTs): may show elevated transaminases.
Management
1. Antibiotic Therapy:
- Doxycycline (first-line treatment).
- Azithromycin if doxycycline is contraindicated (e.g., pregnancy).
2. Supportive Care:
- Fluids and electrolyte management.
- Antipyretics for fever control.
3. Prevention:
- Good personal hygiene and insect control measures.
- Avoidance of exposure in endemic areas.
4. Referral:
- Infectious diseases: for complicated or atypical presentations.
- Intensive care: if multi-organ involvement occurs.