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 US, 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, but mortality increases with age and may reach 60% in untreated patients > 50 years.
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 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.
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
Clinical features
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
Doxycycline
Primary treatment of epidemic typhus is doxycycline 200 mg orally once followed by 100 mg twice a day in adults until the patient improves, has been afebrile for 24 to 48 hours, and has received treatment for at least 7 days.
Although some tetracyclines can cause tooth staining in children < 8 years of age, the Centers for Disease Control and Prevention (CDC) advises that a course of doxycycline 2.2 mg/kg orally or IV twice a day is warranted (1). Research indicates that short courses of doxycycline (5 to 10 days, as used for rickettsial disease) can be used in children without causing tooth staining or weakening of tooth enamel (2).
Chloramphenicol 500 mg orally or IV 4 times a day for 7 days is 2nd-line treatment. Oral chloramphenicol is not available in the US, 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.
Довідкові матеріали щодо лікування
1. Centers for Disease Control and Prevention: Information for Healthcare Providers, Typhus Fevers
2. Todd SR, Dahlgren FS, Traeger MS, et al: No visible dental staining in children treated with doxycycline for suspected Rocky Mountain Spotted Fever. J Pediatr 166(5):1246-51, 2015. doi: 10.1016/j.jpeds.2015.02.015. Epub 2015 Mar 17. PMID: 25794784.
Prevention of Epidemic Typhus
Immunization and louse control are highly effective for prevention. However, vaccines are no longer available. Lice may be eliminated by dusting infested people with malathion or lindane. Bedding and clothing should be washed at least once a week in hot water (> 54 C) and dried on high heat. Non-washable clothing and items can be dry-cleaned or sealed in a plastic bag and stored for 2 weeks. Bedding and clothing also can be treated with the insecticide permethrin.
Ключові моменти
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 and may reach 60% in untreated patients > 50 years; 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.
Treat with doxycycline or chloramphenicol.
Brill-Zinsser disease, a mild recrudescence of epidemic typhus, can occur years after the initial infection if host defenses falter.
Хвороба Бріля — Цінсера
Brill-Zinsser disease is a recrudescence of epidemic typhus, occurring years after an initial attack.
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.