Epidemic Typhus

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Presentation :

After an incubation period of 7 to 14 days, fever, headache, and prostration suddenly occur.
- Temperature reaches 40° C in several days and remains high, with slight morning remission, for about 2 weeks.
- Headache is generalized and intense.
- Small, pink macules, which appear on the 4th to 6th day, rapidly cover the body, usually in the axillae and on the upper trunk and not on the palms, soles, and face. Later, the rash becomes dark and maculopapular. In severe cases, the rash becomes petechial and hemorrhagic.
Hypotension occurs in most seriously ill patients. Vascular collapse, renal insufficiency, encephalitic signs, ecchymosis with gangrene, and pneumonia are poor prognostic signs.

Caused by Rickettsia prowazekii and transmitted by body lice when louse feces are scratched or rubbed into bite or other wounds (or sometimes the mucous membranes of the eyes or mouth).
Brill-Zinsser disease, a mild recrudescence of epidemic typhus, can occur years after the initial infection if host defenses falter.

Diagnosis is based on clinical findings and epidemiologic factors; reliable diagnostic tests are not available for acute illness.
- Louse infestation is usually obvious and strongly suggests typhus if history (eg, living in or visiting an endemic area) suggests possible exposure.
Confirmation of infection can be established via indirect immunofluorescence antibody (IFA) assay, immunohistochemistry (IHC), polymerase chain reaction (PCR) assay of blood, plasma, or tissue samples, or culture isolation.
- Serologic tests are the most common means of confirmation and can be used to detect either IgG or IgM antibodies. Diagnosis is typically confirmed by documenting a four-fold rise in antibody titer between acute and convalescent samples.

- Treatment for both primary infection and recurrence Brill-Zinsser disease is Doxycycline 100mg BID for at least 3 days after the fever subsides and until there is evidence of clinical improvement (usually 7–10 days)

Fatalities are rare in children < 10 years, but mortality increases with age and may reach 60% in untreated patients > 50 years.