Epidemic typhus is caused by Rickettsia prowazekii. Symptoms are prolonged high fever, intractable headache, and a maculopapular rash.
(See also Overview of Rickettsial and Related Infections.)
Epidemic typhus is a rickettsial disease.
Humans are the natural reservoir for R. prowazekii, which is prevalent worldwide 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). In the United States, humans occasionally contract epidemic typhus after contact with flying squirrels because fleas or lice on flying squirrels may be vectors.
Fatalities are rare in children < 10 years old, but mortality increases with age.
Symptoms and Signs of Epidemic Typhus
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 fourth to sixth 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.
Splenomegaly sometimes occurs. Hypotension occurs in most seriously ill patients. Vascular collapse, renal insufficiency, encephalitic signs, ecchymosis with gangrene, and pneumonia are poor prognostic signs.
Brill-Zinsser disease, a mild recrudescence of epidemic typhus, can occur years after the initial infection if host defenses falter.
Diagnosis of Epidemic Typhus
History and physical examination
Biopsy of rash with fluorescent antibody staining to detect organisms
Acute and convalescent serologic testing (serologic testing not useful acutely)
Polymerase chain reaction (PCR)
Louse infestation is usually obvious and strongly suggests typhus if history (eg, living in or visiting an endemic area) suggests possible exposure.
For details, see Diagnosis of Rickettsial and Related Infections.
Treatment of Epidemic Typhus
chloramphenicol is not available in the United States, and its use can cause adverse hematologic effects, which requires monitoring of blood indices.
Severely ill patients with epidemic typhus may have a marked increase in capillary permeability in later stages; thus, IV fluids should be given cautiously to maintain blood pressure while avoiding worsening pulmonary and cerebral edema.
Treatment references
1. Centers for Disease Control and Prevention: Information for Healthcare Providers, Typhus Fevers
2. Todd SR, Dahlgren FS, Traeger MS, et alJ Pediatr 166(5):1246-51, 2015. doi: 10.1016/j.jpeds.2015.02.015
Prevention of Epidemic Typhus
Key Points
Epidemic typhus is prevalent worldwide; humans are the natural reservoir.
Infection is transmitted among humans by body lice when louse feces are scratched or rubbed into louse bites, wounds, or mucous membranes.
Small, pink macules rapidly cover the body, later, becoming dark and maculopapular.
Mortality increases with age; vascular collapse, renal insufficiency, encephalitic signs, ecchymosis with gangrene, and pneumonia are poor prognostic signs.
Suspect epidemic typhus based on clinical manifestations and signs of louse infestation and recent residence in or travel to an endemic region; confirm with fluorescent antibody staining of skin biopsy.
Brill-Zinsser disease, a mild recrudescence of epidemic typhus, can occur years after the initial infection if host defenses falter.
Brill-Zinsser Disease
Patients with Brill-Zinsser disease acquired epidemic typhus earlier or lived in an endemic area. Apparently, when host defenses falter, viable organisms retained in the body are activated, causing recurrent typhus; thus, disease is sporadic, occurring at any season or geographic area, and in the absence of infected lice. Lice that feed on patients may acquire and transmit the agent.
Symptoms and signs of Brill-Zinsser disease are almost always mild and resemble those of epidemic typhus, with similar circulatory disturbances and hepatic, renal, and central nervous system changes. The remittent febrile course lasts about 7 to 10 days. The rash is often evanescent or absent. Mortality is nil.
See the Overview of Rickettsial and Related Infections for diagnosis and treatment details.
