Rickettsial Disease

Question 1

Family: Rickettsiaceae

• what are the two major families:
• Bacteriology:
  gram stain?
  where do they live?

Answer 1

Rickettsiaceae, Anaplasmatacea

Gram-negative cell wall
obligate intracellular bacteria
tick, louse, flea

Question 2

Pathogenesis 1: Rickettsia and Orientitia

Answer 2

• Rickettsia and Orientia; - infect blood vessels:

• Causes the cell to engulf the organism 
• The rickettsia produces enzymes to eexcape the vacuole and live in the cytoplasm
• Damge of the endothelial cell in the process; leading to inflammation and damage to the blood vessel (vasculitis lesion) 
	○ Inflammatory and necrosis of the vasculature 
	○ Vasculitis 
	○ Edema; loss of blood volume; shock; systemic organ failure

Question 3

pathogenesis 2: Ehrlichia and Anaplasm

Answer 3

infected leukocytes (macrophages and neutrophilis):

* Induce their own endocytosis
* Don't escape the vacuole, but inhibit the lysosome from fusing
* Extract nutrients through the vacuolar membrane  
* Grow into clusters called - Morula 
* Affect the cell and damaging the cell -- changing way the genes are transcribed 
* Vascular permeability; edema, hypovolemic shock

Question 4

Rocky Mountain Spotted Fever:

• What organisms causes it?
• how is it transmitted?
• where is it endemic?

-

Answer 4

Rickettsia rickettsii

tick-bite transmitted

North, Central, and South America

Question 5

Rocky Mountain Spotted Fever:

• what are the symptoms
• what is a characteristic symptom
• What are the blood findings?
• how is it diagnosed?

Answer 5

high fever, headache, malaise

maculopapular-petechial rash after 3-5 days

normal white blood cell count with left shift; thrombocytopenia

Dx: Clinical/Hx
- Fever, HA, Tick bite
SEROLOGY

Question 6

Rocky Mountain Spotted Fever:

• how does it kill you?
• What is the treatment

Answer 6

Infection of endothelial cells; lymphohistiocytic vasculitis (blood vessel inflammation and damage) results in loss of intravascular fluid
• hypotension and end-organ ischemic injury
• cerebral edema
• pulmonary edema

Treatment – doxycyclin; Tetra

Question 7

Murine Typhus

• what organisms causes it?
• how is it tranismited
• where is it endemic?

Answer 7

(Rickettsia typhi)

Fleas on Rats

Endemic to areas were fleas live with rats

Question 8

Murine Typhus
what are the symptoms?
What are the lab findings?
how is it diagnosed?

Answer 8

• fever, headache, maculopapular rash on trunk
• normal white blood cell count with left shift; thrombocytopenia

dx: clinical (flea exposure, fever, headache), SEROLOGY

Question 9

Murine Typhus
how does it kill you?
what is the treatment?

Answer 9

• underlying pathology – infection of endothelial cells; lymphohistiocytic vasculitis (blood vessel inflammation and damage) results in loss of intravascular fluid
  
  • hypotension
  • end-organ ischemic injury

• treatment – doxycycline

Question 10

What bug causes Human Moncytic Ehrlichiosis (HME)? what cells does it invade? where is it endemic?

what bug causes Human granulocytic anaplasmosis (HGA)? what cells does it invade? where is it endemic?

How are they transmitted?

Answer 10

Ehrlichia chaffeensis: monocytes and macrophages. southeast and southcentral US

Anaplasma phagocytophilum: neutrophils and granulocytes
northeast and upper midwest US, Europe, East Asia

• Tick bite-transmitted

Question 11

HME and HGA –
Symptoms:
Labs:
Dx:

Answer 11

• fever, headache, myalgia

Low white blood cell count with left shift; thrombocytopenia

clinicopathology + Serology

Question 12

HME and HGA –
How does it kill you?
how do you treat?

Answer 12

infection of leukocytes; no vasculitis
• hypotension
• mild hepatitis
• end-organ ischemic injury when severe

• treatment – doxycycline