Description

• Acute infectious diseases caused by 3 species of Rickettsiae:
  • Epidemic typhus: Human-to-human transmission by body louse vector. Primarily in circumstances, such as refugee camps, war, famine, and disaster. Recrudescent disease, occurring years after initial infection, can be a source of human outbreak. Flying squirrels are also a reservoir.
  • Endemic (murine) typhus: Infection by rodents to humans by rat flea bite
  • Scrub typhus: Infection and infestation of chiggers and of rodents to humans by the chigger; primarily in Asia and western Pacific areas
• System(s) affected: Endocrine/Metabolic; Hematologic/Lymphatic/Immunologic; Pulmonary; Skin/Exocrine
• Synonym(s): Louse-borne typhus; Brill-Zinsser disease; Murine typhus

Epidemiology

• Epidemic and endemic typhus: Rare in the US (outside of south Texas)
• Scrub typhus: Travelers returning from endemic areas only (rare)

Incidence
Endemic typhus: <100 cases annually, primarily in states around the Gulf of Mexico, especially south Texas; underreporting suspected

Risk Factors

Exposure to vectors (e.g., during travel to countries where endemic)

Geriatric Considerations
Elderly may have more severe disease.

General Prevention

Avoid vectors for each disease:

• Scrub typhus: Wear protective clothing and use insect repellents.
• Endemic typhus: Practice ectoparasite and rodent control.
• Epidemic typhus: Delousing and cleaning of clothing; vaccine may be considered for those at high risk of exposure (typhus vaccine production has been discontinued in the US).

Etiology

• Epidemic typhus by R. prowazekii
• Endemic typhus by R. typhi
• Scrub typhus by R. tsutsugamushi