Typhus
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Not to be confused with typhoid fever, a distinct disease caused by a different genera of bacteria
Background
- Also known as murine typhus, endemic typhus, and fleaborne typhus
- Caused by Rickettsia typhi
- Gram negative, obligate, intracellular bacterium
- Replicates in epithelial cells of flea's midgut
Vector
- Infection is transmitted by fleas
- Typically rat fleas
- Also Rickettsia felis (indistinguishable from R. typhi) carried by fleas on opossum and cats
- Feces containing R. typhi are deposited into wound made by flea bites
- Found in areas with large populations of urban rats
- United States
- Southern Texas
- Southern California
- Internationally: Tropical/Subtropical urban seaboard regions
- United States
- Seasonal predilection for summer months
- Texas: Spring to summer
- California: Summer to fall
Clinical Features
- Fever, headache, myalgias[1]
- Transmitted by arthropods/ ticks
- Painless eschar at inoculation site imp clue
- Camping, hiking in grassy/ scrub area
- Regional lymphadenopathy, rash
Clinical Features
- Incubation period: 7-14 days
Symptoms
- Variable and non-specific
- Often presents as acute, self-limited illness, with no complications[2]
- Most Common Symptoms
- Fever- can last ~1 week
- Rash
- Macular or maculopapular, blanching, non-pruritic
- Starts centrally and moves to the extremities
- Can involve palms/soles but usually sparing
- Starts 6-7 days after symptom onset (fever onset)
- Headache
- Arthralgias
- Other Symptoms
- Hepatomegally
- Splenomegally
- Cough
- Diarrhea
- Nausea/Vomiting
- Abdominal pain
- Confusion
Differential Diagnosis
Fever in traveler
- Normal causes of acute fever!
- Malaria
- Dengue
- Leptospirosis
- Typhoid fever
- Typhus
- Viral hemorrhagic fevers
- Chikungunya
- Yellow fever
- Rift valley fever
- Q fever
- Amebiasis
- Zika virus
Evaluation
- leukopenia, thrombocytopenia
- Usually clinically
Management
- Tetracycline
- Chloramphenicol may be an alternative, though associated with higher morbidity
- Confirm serologically, not useful in acute phase
Disposition
See Also
References
- ↑ CDC. Typhus and related diseases. http://wwwnc.cdc.gov/travel/yellowbook/2016/infectious-diseases-related-to-travel/rickettsial-spotted-typhus-fevers-related-infections-anaplasmosis-ehrlichiosis
- ↑ Civen R, Ngo V, 2008. Murine typhus: an unrecognized suburban vectorborne disease. Clin Infect Dis 46: 913–918.
Differential Diagnosis
- Non-specific viral illness
- Most common admitting diagnosis in one case study was "fever of unknown origin"[1]
Tick Borne Illnesses
- Babesiosis
- Colorado tick fever
- Ehrlichiosis
- Heartland virus
- Lyme
- Murine typhus
- Rocky mountain spotted fever
- Southern tick-associated rash illness (STARI)
- Tick paralysis
- Tularemia
Fever in traveler
- Normal causes of acute fever!
- Malaria
- Dengue
- Leptospirosis
- Typhoid fever
- Typhus
- Viral hemorrhagic fevers
- Chikungunya
- Yellow fever
- Rift valley fever
- Q fever
- Amebiasis
- Zika virus
Evaluation
Work up
- Infectious work up
- Not sensitive or specific
- CBC- can show anemia and thrombocytopenia
- LFTs- often elevated 3-5x normal
- Lumbar Puncture- resembles aseptic meningitis
Diagnostic labs
- Immunofluorescent assay is the gold standard
- Becomes diagnostic with time. Rarely positive at onset of illness.
- PCR
Management
- Doxycycline 100mg BID continue for 3 days after resolution of symptoms[2]
- Children - 2.2mg/kg BID
- Chloramphenicol 50-100mg/kg/day div Q6hr (Max dose = 4g/day)