Lecture 31 Rickettsia Flashcards
Describe Q Fever pathnogenesis
1) Infects macrophage by phagocytosis
2) Forms phagocytic vessicle and allow phagosome lysosome fusion
3) Bacterium survives and multiples (No morula)
Describe Ehrlichiosis Pathenogenesis
- Ehrlichia start infection by inducing phagocytosis
- Forms phagocytic vesicle but prevents phagosome-lysosome fusion
- Replicates in the phagosome, forming morula (inclusion body containing organism)
Human Granulocytic Anaplasmosis (HGA) is caused by?
Anaplasma phagocytophilum
Clinical Manifestations: Rocky Mountain Spotted Fever
What causes rashes in RMSP?
As bacteria continues to replicate in the endothelial cells, it causes focal areas of obstruction (small thrombi) that weakens the vascular wall and cause leakage of RBC which causes rash
Clinical Manifestations: Rocky Mountain Spotted Fever
Describe the progression of Rocky Mountain Spotted Fever
Begins on hands and feet and spreads inward to trunk (out to in)
Q Fever is caused by?
Coxiella burnetii
Human Monocytic Ehrlichiosis (HME) is caused by?
E. chaffeensis
Human Granulocytic Ehrlichiosis (HGE) is caused by?
E. ewingii
Describe Ehrlichiosis
Name different types
Ehrlichiosis is an infection of WBC
Types:
1. Human Monocytic Ehrlichiosis (HME)
- Human Granulocytic Ehrlichiosis (HGE)
- Human granulocytic anaplasmosis (HGA)
R. typhi Causes
Endemic (Murine) Typhus
R. prowazekii causes?
Transmission?
Epidemic Typhus
Transmission: body louse (you scratch to allow infection in the body)
Population at risk to Q Fever
Farmers, butchers, vetnarians
Clinical Manifestations: Epidemic Typhus
Describe symptoms of Epidemic Typhus and progression of the disease
Fever, chills, headache, myalgia after about 8 days
Maculopapular rash on trunk and spreads to extremities
Describe Coxiella burnetii
Gram stain
Living patterns
Gram negative bacteria
Lives inside acidic lysosomes
Has “spore-like” characteristics making them stable in environment
Diagnosis: Rocky Mountain Spotted Fever
Describe Stain
Describe Serology
Stain: Gram stain: stains poorly Giemsa, Gimenez Fluorescent antibody for biopsy tissue specimen Serology: Weil-Felix IFA
Describe Coxiella Immunopathogenesis
LPS for Coxiella undergoes antigenic variation which mutates phase I antigen and phase II antigen is produced.
Ab response is marker for acute and chronic diseases
LPS is not toxic. It is used for diagnosis
Phase II antigens used for acute Q fever
Phase I and II antigens used for chronic Q fever
Vector for Rickettsialpox?
Commonly found in?
Mouse mites
Found in Northeast U.S. cities
Describe Rickettsiae: Name of the 4 Genus we are responsible for: Gram Stain: Shape: Life Style:
Name of the 4 Species we are responsible for knowing:
Rickettsia, Ehrlichia, Anaplasma, and Coxiella
Gram Stain:
Gram-Negative
Shape:
Aerobic Coccobacilli (Rods)
Life Style:
Aerobic Small Obligate Intracellular (maintained in animal and arthropod reservoirs)
Scrub Typhus is caused by?
Transmission?
Orientia (Rickettsia) tsutsugamushi
Transmitted by chiggers (mite larvae)
Describe diagnosis differentiation between acute and chronic Q fever
Phase II antigens used for acute Q fever
Phase I and II antigens used for chronic Q fever
Function of Phospholipase A
Phospholipase A degrades phagosome
Epidemic Typhus caused by
R. prowazekii
R. rickettsii Pathogenesis:
How to they infect?
Virulence Factor?
R. rickettsii Pathogenesis: How to they infect? 1. Enter through bite/abrasion 2. Infect endothelial cell by stimulating phagocytosis 3. Degrade Phagosome and enter cytoplasm Virulence Factor? Only Phospholipase A
Rocky Mountain Spotted Fever is caused by what bacteria?
Transmission?
R. rickettsii
Transmitted by Ticks (main reservoir) and wild rodents
Endemic (Murine) Typhus is caused by?
R. typhi
Primary reservoirs for R. typhi is?
Transmission?
Rats are primary reservoir
Transmitted by rat flea
Clinical Manifestations: Brill-Zinsser Disease
Describe symptoms of Brill-Zinsser Disease and progression of the disease
Recrudescent Epidemic Typhus
Symptoms are similar but milder than Epidemic Typhus
Occurs much after initial infection from epidemic typhus
Rickettsialpox is caused by?
Rickettsia akari
Rocky Mountain Spotted Fever is commonly found in?
Why is it called Rocky Mountain Spotted Fever?
Rocky Mountain Spotted Fever is commonly found in the Southeast
Rocky Mountain is where the disease was first discovered
Diagnosis for Ehrlichiosis?
Serological test (IFA) Wright stained blood smears to detect Morulae
Mainly, looking for geography, hemolytic patterns, and morula
What is the primary test for Epidemic Typhus?
Serology
- Positive Weil-Felix
Genus Rickettsia Replicates in?
The Cytoplasm
Coxiella urnetii Infection
Through inhalation
Infects animals (goats, sheep, cattle, and cats)
- found in placenta and fecese of infected livestock
Ticks are NOT common vectors
Ehrlichiosis is transmitted by?
Ticks!
Diagnosis: Rocky Mountain Spotted Fever
Why is Weil-Felix used in serology to identify RMSF even though it is not specific for the bacteria?
Weil-Felix is used to identify RMSF along with associated symptoms
Ths allows the patient to be treated as soon as possible since delayed treatment may lead to complications
Rickettsia akari causes?
Rickettsialpox
