Vector-borne bacterial infections Flashcards
Which bacterial species causes Rocky Mountain Spotted Fever (RMSF)?
Rickettsia Rickettsii, a weekly / non-staining Gram negative bacillo-cocci (oval).
What is the vector for the bacteria causing Rocky Mountain Spotted Fever?
The Tick (Dermacentor)
What bacterial species causes (epidemic) Typhus?
Rickettsia prowazekii, a weekly / non-staining Gram negative bacillo-cocci (oval).
What is the vector for the bacteria causing Typhus?
The human louse.
What bacteria causes Rickettsial pox?
Rickettsia akari
What is the vector and reservoir for Rickettsial pox?
Mites are the vector and mice the reservoir.
What is the clinical presentation of Rickettsial pox?
1) Bite -> nodule / papule.
2) Flu-like symptoms.
3) Rash
4) Bite becomes necrotic eschar.
1) What is the treatment for all Rickettsial diseases ?
2) Which disease is most lethal and which does not require treatment?
1) Doxycycline.
2) RMSF can be lethal within a week, do not wait for confirmed diagnosis. Treat upon suspicion. Rickettsial pox however usually goes away on its own.
What do “flu-like symptoms” between Spring and Fall suggest?
These symptoms suggest a Rickettsial disease.
Fever, headache, chills, myalgias, etc.
What symptom is highly suggestive of RMSF?
A rash that covers palms and soles and spreads from periphery inwards.
What symptom suggests Typhus?
A rash that spreads outwards from the core.
What lab findings are characteristic of Rickettsial disease?
Thrombocytopenia, high LTFs, neutropenia, hyponatremia (low Na).
What is the main pathogenic mechanism of Rickettsia rickettsii?
Vasculitis (endothelial damage) causes rash, petechiae, purpura, and leads to multi-organ system failure.
What are the two forms of Ehrlichioses?
What bacteria causes them?
Human Monocytic Ehrlichiosis (Erhlichia chaffeensis)
Human Granulocytic Anaplasmosis (Anaplasma phagocytophilum)
What is a characteristic finding under a microscope of a leukocyte (either granulocyte or monocyte) infected with HME or HMA?
An intracellular “morulae” or mulberry cluster of Erhlichia chaffeensis or Anaplasma phagocytophilum.
What is the vector for the Ehrlichioses?
The ixode tick
Treatment for Anaplasmosis and Ehrlichiosis?
Doxycycline
What does a halo shaped rash (erythematous ring called Erythema migrans) around a nodule/papule/bite suggest?
Lyme disease.
What is the bacteria responsible for Lyme disease and what is its vector?
Borrelia burgdorferi is a gram-negative spirochete carried by the Ixode tick and causes Lyme.
Why do “tick checks”?
Because the tick must be attached (feeding) for 24hrs in order to transmit Borrelia burgdorferi.
What are the stages of Lyme disease?
1) Early localized - erythema migrans.
2) Early disseminated - Bell’s palsy (CN VII), meningitis, arthritis, heart block, pericarditis.
3) Late disseminated - Migratory polyarthritis, encephalopathy, meningitis.
What stains can be used to visualize Borrelia burgdorferi?
Wright’s stain or Giemsa stain.
