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 Historical references to "typhus" are now generally considered to be this condition.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

Epidemic typhus

• Fever, headache, myalgias
• 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
  • Ebola virus disease
  • Marburg virus disease
  • Lassa fever
  • Crimean-Congo hemorrhagic fever
• 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

See Also

• Travel Medicine

References

Authors

Ross Donaldson