Rickettsia

Question 1

Rocky Mountain Spotted Fever Cause

Answer 1

Rickettsia rickettsii

Question 2

Rickettsialpox Cause

Answer 2

R. akari

Question 3

Epidemic typhus (louse-borne typhus) Cause

Answer 3

R. prowazekii

Question 4

Brill-Zinsser disease Cause

Answer 4

R. prowazekii

Question 5

Murine typhus Cause

Answer 5

R. typhi

Question 6

Scrub typhus Cause

Answer 6

Orientia tsutsugamushi

Question 7

Two types of Ehrlichiosis

Answer 7

Human Anaplasmosis

Human Monocyte Ehrlichiosis

Question 8

Human Anaplasmosis Cause

Answer 8

Anaplasma phagocytophilium

Ehrlichia ewingii

Question 9

Human Monocyte Ehrlichiosis Cause

Answer 9

E. chaffeensis

Question 10

Q fever Cause

Answer 10

Coxiella burnetii

Question 11

What is the reservoir of R. rickettsii?

Answer 11

Dogs and rodents

Question 12

What is the vector of R. rickettsii?

Answer 12

Ticks (Dog and Wood)

Question 13

How is R. rickettsii maintained in the tick population?

Answer 13

Maintained in the tick population by passage from tick to tick through transovarian transmission

Question 14

What are the manifestations of RMSF?

Answer 14

High fever and headache
Rash most characteristic feature
i. Rash present particularly on hands and feet
ii. Rash moves from extremities to trunk of body

Question 15

Where does RMSF occur most often?

Answer 15

Main states are NC and OK

Occurs in association with residential and recreational exposure to wooded areas where infected ticks exist

Question 16

What is the reservoir of rickettsialpox?

Answer 16

Mites (possibly mice)

Question 17

What is the vector of rickettsialpox?

Answer 17

Mites

Question 18

How is R. akari maintained in mites?

Answer 18

Transovarian transmission

Question 19

What are the manifestations of rickettsial pox?

Answer 19

Phase 1: A firm red papule appears at the site of the bite. Papule develops into deep-seated vesicle then black eschar

Phase 2: Systemic spread and after 9-14 days, high fever, severe headache, chills/sweats, myalgias, photophobia develop. A vesicular rash develops (small, blister like lesions filled with clear fluid).

Question 20

What is the reservoir of epidemic typhus?

Answer 20

Reservoirs include humans and flying squirrels

Question 21

What is the vector of epidemic typhus?

Answer 21

Lice

Question 22

How is R. prowazekii maintained in lice?

Answer 22

Lice die after 2-3 weeks, thus preventing transovarian transmission. It is NOT maintained.

Question 23

How is epidemic typhus spread?

Answer 23

Organisms are present in the feces of the infected lice and enter through the bite would or skin abrasions

Question 24

What are the manifestations of epidemic typhus?

Answer 24

Fever and headache
Maculopapular rash begins first on the trunk and then spreads centripetally to the extremities (opposite to Rocky Mountain Spotted fever)

Question 25

What are the manifestations of Brill-Zinsser disease?

Answer 25

Relapse of louse-borne typhus appearing 10-40 years after the primary attack. Rickettsia persist for many years in the lymph nodes of an individual without any symptoms being manifest.

Question 26

What is the reservoir of murine typhus?

Answer 26

Rodents

Question 27

What is the vector of murine typhus?

Answer 27

Fleas

Question 28

What are the manifestations of murine typhus?

Answer 28

Fever, severe headache, chills, myalgia, nausea | Rash in 50% of cases, typically restricted to the chest and abdomen, but may extend to palms and soles.

Question 29

Where is scrub typhus found?

Answer 29

Southwest Pacific, Southeast Asia, and Japan

Question 30

What is the reservoir of scrub typhus?

Answer 30

Mites

Question 31

What is the vector of scrub typhus?

Answer 31

Mites

Question 32

What are the clinical manifestations of scrub typhus?

Answer 32

Typical initial lesion, a necrotic eschar at the site of the bite on the extremities, develops in only 50 to 80% of the cases. Generalized lymphadenopathy

Question 33

What is the reservoir of HME?

Answer 33

White-tailed deer and dogs

Question 34

What is the vector of HME

Answer 34

Lone Star Tick

Question 35

Where is HME found?

Answer 35

HME found in U.S. predominantly in southeastern, mid-Atlantic and south central states; OK has high rate of incidence

Question 36

What is the reservoir of HA?

Answer 36

Rodents

Question 37

What is the vector of HA?

Answer 37

Ixodes Tick

Question 38

Where is HA found?

Answer 38

Human anaplasmosis found in U.S. primarily in northern and central midwestern states and northeast and central Atlantic states.

Question 39

What are the manifestations of HA and HME?

Answer 39

Fever, chills, headache, myalgia, nausea or vomiting Typically NO rash Leukopenia, thrombocytopenia, and elevated serum transaminases develop in majority of patients

Question 40

What are the manifestations of HME?

Answer 40

Late onset rash in 30-40%

Question 41

What are the manifestations of HA?

Answer 41

Infection primarily of bone marrow myeloid cells

Question 42

What is the reservoir of Q fever?

Answer 42

Carried by mammals such as cattle, sheep, and goats

Question 43

How does infection by C. burnettii occur?

Answer 43

Infection is believed to typically occur through inhalation of dust contaminated with Coxiella or from aerosols in slaughterhouses

Question 44

What are the manifestations of Q fever?

Answer 44

A mild, dry, hacking cough and patchy interstitial pneumonia may or may not be present. NO rash

Question 45

What is the pathogenesis of Q fever?

Answer 45

C. burnetii primarily replicates in the phagosome because it requires low pH. C. burnetii forms endospores and thus is resistant to drying and other environmental conditions.

Question 46

How does Coxiella burnetii pathogenesis differ from Rickettsial organisms such as Rickettsia rickettsii?

Answer 46

Coxiella enters via a phagolysosome-like vesicle wheres Rickettsia enters the cytoplasm. The phagosome fuses with endosomes as Coxiella requires low pH for growth. Outside of the cells Coxiella is viable for years but Rickettsia quickly dies.

Question 47

What organisms exit the cell by budding?

Answer 47

R. rickettsia and R. typhi They escape using Phospholipase A and multiply in cytoplasm. R. rickettsia and R. typhi then migrate intracellularly using actin polymerization.

Question 48

After returning from an extended stay at her Aunt Sarah's cattle ranch in Oklahoma, 12-year old Susie complains of cold-like symptoms: severe headache, high fever, myalgia, and a persistent cough. You see no signs of rash. Laboratory results indicate the presence of bacteria, but normal white blood cells. You conclude that the causative agent of this disease was transmitted to Susie: A. By a bite from a blood sucking mite B. Through exposure to the wood tick Dermacentor andersoni C. By breathing dust from the cattle. D. From Aunt Sarah’s persistent cough E. Through a louse bite

Answer 48

C. By breathing dust from the cattle.