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29 Cards in this Set
- Front
- Back
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How is Rickettsia transmitted?
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Ricks, fleas, lice, and chiggers
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How is Ehrlichia/anaplasma transmitted?
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Ticks
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How is Coxiella transmitted?
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Ticks and aerosol ingestion
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Where are Rickettsia, Ehrlichia/anaplasma, and Coxiella found in the body?
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Inside cells (obligate intracellular bacteria)
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What is the major rickettsia disease?
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Rocky mountain spotted fever
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What disease does coxiella cause?
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Q fever
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Describe the pathogenicity of rickettsia?
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Mainly infects endothelial cells
Produces free radicals, which cause damage to the endothelial cell membrane and thus vascular leak. This activates the coagulation cascade and slight hemorrhage, forming petechiae all over the body. Replicates in host cell nucleus |
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What is the outcome of rocky mountain spotted fever?
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May cause encephalitis with CNS endothelial infection
25% mortality rate if untreated 7% if treated |
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What does R. rickettsii cause? How is it transmitted?
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Rocky mountain spotted fever
Transmitted by ticks |
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What are the signs and symptoms of rocky mountain spotted fever?
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Fever
Rash History of tick bite (all of these three happen in about 1/3 of cases) Headach |
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How do you diagnose rocky mountain spotted fever?
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CLINICALLY (look for triad)
Immunohistopathology (of rash) is also useful |
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How do you treat RMSF (and all other rickettsiae)?
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Doxycycline
Fluoroquinolones also work |
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What causes epidemic typhus?
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Rickettsiae prowazekii
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What is the reservoir for epidemic typhus?
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Humans and flying squirrels
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What is the vector for epidemic typhus?
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Human lice (feces)
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How do you diagnose R. prowazekii?
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Associated with disasters (war, famine, refugees)
Rash like in RMSF |
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What causes endemic (murine) typhus?
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Rickettsiae typhi
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What is the reservoir in endemic (murine) typhus?
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Rodents (murine means mouse)
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What is the vector of endemic (murine) typhus?
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fleas (feces)
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What causes human monocytic erhlichiosis (HME)?
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Erhlichia chaffeensis
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What causes human granulocytic erhlichiosis (HGE)?
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Anaplasma phagocytophilum
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How do you treat human monocytic erhlichiosis?
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Doxycycline
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How do you treat human granulocytic erhlichiosis?
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Doxycycline
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How do you distinguish between rocky mountain spotted fever and erhlichiosis?
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Petechial rash in RMSF
Leukopenia in erhlichiosis |
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What are the similarities between rocky mountain spotted fever and erhlichiosis? (4)
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History of tick bite
Geographic location of cases Elevated liver enzymes Response to doxycycline |
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Describe the epidemiology of Coxiella burnetii.
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Forms a spore that can withstand harsh conditions
Usually enters by inhalation (infectious dose - 1 inoculum) Obligate intracellular parasite (survives in a phagolysosome) |
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What is the reservoir for coxiella?
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Cattle, sheep, horses, and house cats
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How is coxiella transmitted?
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By ticks
Often aerosolized while giving birth (placenta hitting the ground) |
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What is the clinical presentation of Q fever?
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Flu-like illness
Atypical pneumonia Could cause endocarditis and hepatitis |
