Epidemic typhus
Not to be confused with typhoid fever, a distinct disease caused by a different genera of bacteria
Background
- Also known as epidemic "louse-borne" typhus
- Any of several similar diseases caused by Rickettsia bacteria (e.g. Rickettsia prowazekii, )
Types of Typhus
Multiple diseases include the word "typhus" in their description. Types include:
| Condition | Bacteria | Reservoir/vector | Notes |
|---|---|---|---|
| Epidemic "Louse-borne" typhus | Rickettsia prowazekii | Human Body louse | When the term "typhus" is used without clarification, this is usually the condition described. Historical references to "typhus" are now generally considered to be this condition. |
| Murine typhus or "endemic typhus" | Rickettsia typhi | Fleas on rats | |
| Scrub typhus | Orientia tsutsugamushi | Harvest mites on humans or rodents | Unlike the two conditions above, though it has the word "typhus" in the name, it is currently usually not classified in the typhus group, but in the closely related spotted fever group. |
| Queensland tick typhus | Rickettsia australis | Ticks |
Clinical Features
- Fever, headache, myalgias[1]
- Transmitted by arthropods/ ticks
- Painless eschar at inoculation site imp clue
- Camping, hiking in grassy/ scrub area
- Regional lymphadenopathy, rash
Differential Diagnosis
Fever in traveler
- Normal causes of acute fever!
- Malaria
- Dengue
- Leptospirosis
- Typhoid fever
- Typhus
- Viral hemorrhagic fevers
- Chikungunya
- Yellow fever
- Rift valley fever
- Q fever
- Amebiasis
- Zika virus
Evaluation
- leukopenia, thrombocytopenia
- Usually clinically
Management
- Tetracycline
- Chloramphenicol may be an alternative, though associated with higher morbidity
- Confirm serologically, not useful in acute phase