Rickettsial diseases and friends Flashcards
What other bacteria is Rickettsia similar to?
Chlamydia
Describe Rickettsiae
What does the cell cell resemble?
Where is it found?
Where do they infect?
- 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)
What are the vectors for the following: rocky mountain spotted fever epidemic typhus endemic typhus rickettsialpox
rocky mountain spotted fever- tick
epidemic typhus-louse
endemic typhus-flea
rickettsialpox-mouse
Why do most rickettsial diseases cause a rash and vasculitis? How?
- 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
What are common sx of Rickettsiae diseases?
What are the quick lab tests?
**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
So how do you dx Rickettsial diseases?
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!
What are the rickettsial diseases in the USA?
Rocky Mountain Spotted Fever
Rickettsial pox
Endemic Flea-borne typhus
epidemic louse-borne thypus
Rocky mountain spotted fever (RMSF)
- what is the pathogen?
- where is it found?
- insect vector?
- other carriers?
- Rickettsia rickettsii
- mid-atlantic coast
- tick
- rodents, dogs
Epidemic (Louse-borne) Typhus
- what is the pathogen?
- where is it found?
- insect vector?
- other carriers?
- Rickettsia prowazekii
- central and northeastern africa, central and south america
- louse
- Flying squirrels
Endemic (murine) typhus
- Rickettsia typhi
- small focus in US, southeastern gulf
- flea
- Rodents
Rickettsial pox
- what is the pathogen?
- where is it found?
- insect vector?
- other carriers?
- Rickettsia akari
- US
- Mite
- Mice
- causes an eschar
RMSF
sx
what other diseases do these sx resemble?
describe rash
- 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
What lab tests would you want to work up RMSF? What would you expect to see from those tests?
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
RMSF
tx
DOXYCYCLINE (DOC)
delay in tx can lead to severe disease and death
Flying squirrels are an extra-human reservoir for what? What disease does it cause?
Rickettsia prowazekii
causes Epidemic louse-borne typhus
Epidemic louse-borne typhus sx lab findings What can this lead to? tx
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)
Endemic (Murine) Typhus
- what is the pathogen?
- transmission
- sx
- lab findings
- tx
- 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)
Rickettsialpox
- what is the pathogen
- transmission
- sx
- tx
- 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
Q fever
- what is the pathogen?
- transmission
- sx
- lab findings
- tx
- 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
What would the combination of pneumonia and hepatitis suggest?
Q FEVER
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?
-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
Lyme Disease
sx
dx
tx
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
