Murine typhus (R. typhi)

Disease caused by the flea-borne Gram-negative intracellular bacterium Rickettsia typhi

Life Cycle

Flea vector (Xenopsylla cheopis) with a rat reservoirs (Rattus spp.)
- Also, cat flea vector (Ctenocephalides felis) in sourthern US
- Possibly opossums as reservoirs
Worldwide distribution
In the US, most cases are in southern Texas and California

Incubation period of 1 to 2 weeks, but rarely remember flea exposure
Fever, headache, nausea and vomiting are common, as well as myalgias
Rash develops over the course
- Usually described as maculopapular, sometimes with petechiae
- On trunk, but can involve extremities
- Rarely on palms and soles
May have leukopenia and thrombocytopenia early in the course
Elevated AST is common, as well as other liver enzymes
Further nausea/vomiting and anorexia, cough, and hepatosplenomegaly may all develop
Neurologic complications include confusion, seizures, and ataxia
They often develop hypoalbuminemia and electrolyte abnormalities such as hyponatremia and hypocalcemia
CSF shows aseptic meningitis
1 to 4% mortality
Sort of like a milder version of R. prowazekii