Murine typhus: Difference between revisions
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''Also known as "endemic typhus" and "fleaborne typhus"'' | |||
==Background== | |||
*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 | |||
*Seasonal predilection for summer months | |||
**Texas: Spring to summer | |||
**California: Summer to fall | |||
==Clinical Features== | |||
*Incubation period: 7-14 days | |||
[[File:Murine_Typhus.png|thumb|Rash of Murine Typhus]] | |||
===Symptoms=== | |||
*Variable and non-specific | |||
*Often presents as acute, self-limited illness, with no complications<ref>Civen R, Ngo V, 2008. Murine typhus: an unrecognized suburban vectorborne disease. Clin Infect Dis 46: 913–918.</ref> | |||
;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== | |||
*Non-specific viral illness | |||
*Most common admitting diagnosis in one case study was "fever of unknown origin"<ref>Civen R, Ngo V, 2008. Murine typhus: an unrecognized suburban vectorborne disease. Clin Infect Dis 46: 913–918.</ref> | |||
{{Tick borne illnesses DDX}} | |||
{{Template:Fever in Traveler DDX}} | |||
==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<ref>Civen R, Ngo V, 2008. Murine typhus: an unrecognized suburban vectorborne disease. Clin Infect Dis 46: 913–918.</ref> | |||
**Children - 2.2mg/kg BID | |||
*[[Chloramphenicol]] 50-100mg/kg/day div Q6hr (Max dose = 4g/day) | |||
==See Also== | |||
*[[Typhus]] | |||
==External Links== | |||
==References== | |||
<references/> | |||
[[Category:ID]] | |||
Revision as of 10:05, 19 December 2016
Also known as "endemic typhus" and "fleaborne typhus"
Background
- 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
- Incubation period: 7-14 days
Symptoms
- Variable and non-specific
- Often presents as acute, self-limited illness, with no complications[1]
- 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
- Non-specific viral illness
- Most common admitting diagnosis in one case study was "fever of unknown origin"[2]
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[3]
- Children - 2.2mg/kg BID
- Chloramphenicol 50-100mg/kg/day div Q6hr (Max dose = 4g/day)
See Also
External Links
References
- ↑ Civen R, Ngo V, 2008. Murine typhus: an unrecognized suburban vectorborne disease. Clin Infect Dis 46: 913–918.
- ↑ Civen R, Ngo V, 2008. Murine typhus: an unrecognized suburban vectorborne disease. Clin Infect Dis 46: 913–918.
- ↑ Civen R, Ngo V, 2008. Murine typhus: an unrecognized suburban vectorborne disease. Clin Infect Dis 46: 913–918.