Summary
Typhus is an umbrella term for three zoonitic diseases caused by bacteria in the family Rickettsiaceae. Endemic (murine) typhus is caused by Rickettsia typhi transmitted by rat and cat fleas. Epidemic typhus is caused by Rickettsia prowazekii transmitted by the body louse. Scrub typhus is caused by Orientia tsutsugamushi transmitted by chiggers. All three types of typhus manifest with flu-like symptoms and can cause a maculopapular rash that spreads from the trunk to the extremities. Symptoms in epidemic typhus are often more severe and can include neurological symptoms (e.g., seizures). Features unique to scrub typhus include lymphadenopathy and eschar that can develop at the site(s) of infection. Confirmatory testing, e.g., with an indirect fluorescent antibody (IFA) test, is not required before starting treatment for clinically suspected cases. Doxycycline is the first-line treatment for all types of typhus, and early treatment can mitigate the severity of illness and complications.
Endemic (murine) typhus
Epidemic typhus and scrub typhus are described separately.
Background [1]
- Epidemiology: occurs worldwide; mainly in warm coastal regions, e.g., southern US and Hawaii
- Pathogen: Rickettsia typhi
- Transmission: : exposure to infected rat and cat fleas [2]
- Incubation period: 7–14 days [1]
Clinical features [1]
- Fever, severe headache, malaise
- Maculopapular or petechial rash erupts on the trunk and spreads to the extremities (palms and soles are spared). [1]
- Nausea, vomiting, abdominal pain
- Cough
- Altered mental status
The rash of Typhus starts on the Trunk.
Diagnostics [2]
Suspect the diagnosis in patients with clinical features and relevant exposure history.
-
Routine studies
- CBC: leukocytosis or leukopenia, anemia, thrombocytopenia
- Liver chemistry: ↑ ALT and AST (3–5 times ULN), ↓ albumin [2]
- Inflammatory markers: ↑ ESR
-
Confirmatory tests
- Gold standard: IFA test demonstrating a four-fold rise in rickettsial antibodies when comparing a sample taken during the first week of illness to a convalescent sample taken 2–4 weeks later.
- Other modalities, e.g.: enzyme immunoassay (EIA), PCR, and Weil-Felix test
Consider reporting suspected cases to the state or local health department (based on local practice).
Treatment [1]
Initiate treatment early in all clinically suspected cases.
- First-line: doxycycline [1]
- Alternatives (e.g., during pregnancy): chloramphenicol or a quinolone [2]
Epidemic typhus
Murine typhus and scrub typhus are described separately.
Background [1]
-
Epidemiology
- Most common in central and eastern Africa, central and South America, and Asia [1][3]
- Extremely rare in the US
- Pathogen: Rickettsia prowazekii
- Transmission: direct contact with persons and/or fabrics infested with human body lice [1]
- Incubation period: 8–16 days [1]
-
Recrudescent infection (Brill-Zinsser disease) [3]
- Reactivation of latent infection with R. prowazekii that occurs months to years after the initial infection
- Triggered by extreme stress or immunosuppression; unrelated to louse infestation
Clinical features [3]
Acute infections and Brill-Zinsser disease have similar clinical presentations.
- Abrupt onset of fever, severe headache, malaise, myalgia, abdominal pain, nausea, cough
- Maculopapular or petechial rash that spreads from the trunk to the extremities 4–5 days after the onset of fever [1]
- Neurological symptoms (e.g., confusion, coma, seizures) and/or vasculitis in advanced untreated disease
The rash of Typhus starts on the Trunk.
Diagnostics [1]
Suspect the diagnosis in patients with clinical features and relevant exposure history, or a history of prior infection.
-
Routine studies [3]
- CBC: thrombocytopenia
- BMP: ↑ BUN
- Liver chemistry: ↑ ALT and AST, ↑ bilirubin
-
Confirmatory tests: for acute and recrudescent infections
- IFA test demonstrating a four-fold rise in rickettsial antibodies when comparing a sample taken during the first week of illness to a convalescent sample taken 2–4 weeks later.
- Other modalities, e.g.: EIA, PCR, Weil-Felix test [3]
Treatment
Initiate treatment early in all clinically suspected cases.
- First-line: doxycycline [1]
- Alternative (e.g., during pregnancy): chloramphenicol [3]
Scrub typhus
Epidemic typhus and murine typhus are described separately.
Background [1]
- Epidemiology: Occurs mainly in central, eastern, and southeast Asia, as well as northern Australia and South Pacific
- Pathogen: Orientia tsutsugamushi
- Transmission: exposure to vegetation harboring infected larval mites (Leptotrombidium spp.)
- Incubation period: 7–10 days
Clinical features [1]
- Fever, severe headache, myalgias, arthralgia, cough
- Maculopapular rash spreading from trunk to extremities
- Eschar at site of mite attachment may be observed
- Lymphadenopathy
- Altered mental status
- Relative bradycardia despite fever [4]
- Multiorgan dysfunction syndrome in severe cases
The rash of Typhus starts on the Trunk.
Diagnostics [1]
Suspect the diagnosis in patients with clinical features and relevant exposure history.
-
Routine studies
- CBC: thrombocytopenia
- BMP: ↑ creatinine
- Liver chemistry: ↑ ALT and AST, ↑ bilirubin
-
Confirmatory tests
- Gold standard: IFA test demonstrating a four-fold rise in rickettsial antibodies when comparing a sample taken during the first week of illness to a convalescent sample taken 2–4 weeks later.
- Other modalities, e.g.: ELISA, indirect immunoperoxidase assay, PCR, and Weil-Felix test
Treatment
Initiate treatment early in all clinically suspected cases.
- First-line: doxycycline [1]
- Alternatives (e.g., during pregnancy): chloramphenicol, azithromycin, rifampin [1]