Background
Microbiology
Life Cycle
- Adult louse becomes infected when feeding on a rickettsemic patient
- The louse poops on another person
- The person scratches their skin or touches their mucous membrane, innoculating themselves with louse feces
Epidemiology
- Carried by the human body louse, Pediculus humanus corporis
- Outbreaks are associated with poverty, refugee camps, jails, and cold climate
- The only non-human reservoir is the flying squirrel (Glaucomys volans) in the US
- Previously-infected patients may still have latent infection
Clinical Manifestations
- Incubation period 1 to 2 weeks
- High fever, severe headache, myalgia, non-producive cough, delirium
- Dull, red rash starting on the trunk and spreading peripherally
- Spares palms and soles
- Rash not always present
- Delirium, hemorrhagic rash
- In its severe form, can progress to pulmonary edema, encephalitis, shock, and death
Brill-Zinsser disease (BZD)
- Reactivation or recrudescence of dormant typhus years after the initial infection
- Often in the context of malnutrition, chronic illness, and poor hygeine
- Rash may be evanescent or absent, and resolves faster
Diagnosis
- Four-fold rise in indirect immunofluorescence assay for IgG
- PCR may be useful during acute illness
Management
- Need to treat even without confirmed diagnosis
- Doxycycline 100 mg po bid for 7 to 10 days, until afebrile for 24 to 48 hours
- Chloramphenicol is the alternative
- Wash clothing to prevent outbreaks
