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Infectious Disease 3 > Rickettsial diseases and friends > Flashcards

Rickettsial diseases and friends Flashcards

1
Q

What other bacteria is Rickettsia similar to?

A

Chlamydia

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2
Q

Describe Rickettsiae
What does the cell cell resemble?
Where is it found?
Where do they infect?

A
  • obligate intracellular bacterial parasites (steal ATP), they are unable to produce sufficient energy to replicate extracellularly
  • cell wall resembles that of gram-negative
  • Found in arthropods (vector), grow in the gut lining, often without harming the host.
  • They circulate widely in the bloodstream (bacteremia) and infect the endothelium of the blood vessel walls (which is why they produce rashes)
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3
Q 
What are the vectors for the following:
rocky mountain spotted fever
epidemic typhus
endemic typhus
rickettsialpox
A

rocky mountain spotted fever- tick
epidemic typhus-louse
endemic typhus-flea
rickettsialpox-mouse

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4
Q

Why do most rickettsial diseases cause a rash and vasculitis? How?

A
  • Rickettsia has a tropism (preference) for endothelial cells that line blood vessels
  • cause damage to the endothelial cells and the vessels, resulting in a rash
  • edema and hemorrhage caused by increased capillary permeability
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5
Q

What are common sx of Rickettsiae diseases?

What are the quick lab tests?

A

**most Rickettsial diseases cause rashes, high fevers, arthralgia, and bad headaches

  • some cause vasculitis (petechiae, purpura
  • There are no quick lab tests, if takes forever to confirm a dx
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6
Q

So how do you dx Rickettsial diseases?

A

Primary dx method is HISTORY (of insect bite)
-watch for activities that might suggest exposure to ticks (outdoor activities, hiking)

dx also made by physical exam

-confirmation of your clinical dx will be based on measuring immunological titers to the infecting organism and this may take weeks!

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7
Q

What are the rickettsial diseases in the USA?

A

Rocky Mountain Spotted Fever
Rickettsial pox
Endemic Flea-borne typhus
epidemic louse-borne thypus

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8
Q

Rocky mountain spotted fever (RMSF)

  • what is the pathogen?
  • where is it found?
  • insect vector?
  • other carriers?
A
  • Rickettsia rickettsii
  • mid-atlantic coast
  • tick
  • rodents, dogs
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9
Q

Epidemic (Louse-borne) Typhus

  • what is the pathogen?
  • where is it found?
  • insect vector?
  • other carriers?
A
  • Rickettsia prowazekii
  • central and northeastern africa, central and south america
  • louse
  • Flying squirrels
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10
Q

Endemic (murine) typhus

A
  • Rickettsia typhi
  • small focus in US, southeastern gulf
  • flea
  • Rodents
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11
Q

Rickettsial pox

  • what is the pathogen?
  • where is it found?
  • insect vector?
  • other carriers?
A
  • Rickettsia akari
  • US
  • Mite
  • Mice
  • causes an eschar
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12
Q

RMSF
sx
what other diseases do these sx resemble?
describe rash

A
  • acute onset of nonspecific sx (fever, severe HA, myalgias, and prostration)
  • looks kinda like meningitis :/, might be confused with measles, typhoid, ehrlichiosis
  • rash appears 2-6 days later. Macules frequently progress to petechiae. Rash occurs in 90% of children.
  • Rash usually appears on the wrists/ankles first, then hands and soles and moves inward to the trunk
  • Rash can be localized (to just the wrists or whatever)
  • rash might be of short duration
  • Rash is completely absent in up to 20% of RMSF cases
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13
Q

What lab tests would you want to work up RMSF? What would you expect to see from those tests?

A

CBC- thrombocytopenia

Chem panel (CMP) (C-7)-hyponatremia, hyperbilirubenemia, ELEVATED LTFs (unique-good hint that it might be RMSF)

Spinal tap for CSF- low glucose, pleocytosis (increased WBCs in CSF)

Blood cultures

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14
Q

RMSF

tx

A

DOXYCYCLINE (DOC)

delay in tx can lead to severe disease and death

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15
Q

Flying squirrels are an extra-human reservoir for what? What disease does it cause?

A

Rickettsia prowazekii

causes Epidemic louse-borne typhus

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16
Q 
Epidemic louse-borne typhus
sx
lab findings
What can this lead to?
tx
A

sx

  • prodromal malaise, cough, HA, arthralgias, and CP during incubation period of 10-14 days
  • abrupt onset of chills, high fever, and flu-like sx progressing to delirium and stupor

lab findings

  • CBC
  • CMP
  • CXR: patchy consolidation

Brill-Zinsser Disease.

  • R prowazekii can survive in lymphoid tissues after primary infection and, years later, produce recrudescence (recurrence) of disease.
  • more gradual onset that primary. Fever and rash are shorter in duration and the disease is milder and rarely fatal

tx

  • Doxycycline! (grey teeth, bad bones)
  • chloramphenicol (grey baby syndrome, aplastic anemia, optic neuritis)
17
Q

Endemic (Murine) Typhus

  • what is the pathogen?
  • transmission
  • sx
  • lab findings
  • tx
A
  • Rickettsia typhi
  • transmitted from rat to rat via the rat flea

sx
-gradual onset, less severe sx, and shorter duration of illness compared to Epidemic Typhus
(((-prodromal malaise, cough, HA, arthralgias, and CP during incubation period of 10-14 days
-abrupt onset of chills, high fever, and flu-like sx progressing to delirium and stupor)))

lab findings (same as epidemic typhus)

  • CBC
  • CMP
  • CXR: patchy consolidation

tx (same as epidemic typhus)

  • Doxycycline! (grey teeth, bad bones)
  • chloramphenicol (grey baby syndrome, aplastic anemia, optic neuritis)
18
Q

Rickettsialpox

  • what is the pathogen
  • transmission
  • sx
  • tx
A
  • Rickettsia akari
  • transmitted to humans via mites that ride on mice
  • mild, self limited, febrile illness that starts with an initial localized red skin bump
  • Bump turns into a blister and days later fever and the HA develop, and other vesicles appear over the body

-Doxycycline

19
Q

Q fever

  • what is the pathogen?
  • transmission
  • sx
  • lab findings
  • tx
A
  • what is the pathogen?
  • -Coxiella burnetii (gram negative intracellular organism)
  • transmission
  • -Infect CATTLE, SHEEP, and GOATS
  • -Highly resistant spore stage that is transmitted to humans when animal tissue is aerosolized or ingestion of contaminated milk
  • sx
  • -Begins suddenly with fever, severe headache, cough, and other influenza like sx
  • -PNEUMONIA develops in about 50% of pts
  • -HEPATITIS is frequent
  • -could be related to chronic fatigue syndrome
  • -*Culture negative endocarditis is main manifestation of chronic Q fever
  • lab findings
  • -CBC: may have leukocytosis
  • -CMP: elevated LFTs
  • -CXR:worse than the patient appears
  • -Echo: to check for endocarditis
  • tx
  • -Q fever is an acute disease and recovery is expected even in the absence of antibiotic therapy
  • -doxycycline
20
Q

What would the combination of pneumonia and hepatitis suggest?

A

Q FEVER

21
Q

Lyme disease

  • what is the pathogen?
  • what region is this found in?
  • what disease is this similar to?
  • How long does it take to transfer infection?
A 
-what is the pathogen?
Borrelia burgdorferi (corkscrew shaped)

-what region is this found in?
Northeast, midwest, northwest

-what disease is this similar to?
Syphilis

-How long does it take to transfer infection?
24 hours, timeline is very variable

22
Q

Lyme Disease
sx
dx
tx

A

sx

  • Erythema chronicum migrans (bulls eye)
  • regional lymphadenopathy, HA, fever, malaise

dx

  • recognize sx in person from exposed area
  • If ECM, leading edge of rash bx
  • Culture is very difficult
  • ELISA and Western Immunoblotting

tx
-Doxycycline or penicillin

Infectious Disease 3 (9 decks)

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