Rickettsia, Coxiella, Ehrlichia, Anaplasma

Question 1

Rickettsia general characteristics

Answer 1

Gram - bacteria
Obligate intracellular of vasc. endothelium
Stain with Giema

Question 2

R. rickettsii is the causative agent of …

Answer 2

Rocky Mountain Spotted Fever

Question 3

Rickettsia distribution

Answer 3

Throughout US (south central states), southern Canada, Central America, South America (New world)

Question 4

R. rickettsii

Answer 4

Humans and dogs show clinical illness (petechiae)
Cats resistant to RMSF

Question 5

R. felis

Answer 5

Not pathogenic to cats
Zoonotic

Question 6

Rocky Mountain Spotted Fever

Answer 6

Most severe and reported rickettsial illness of humans in the US
Reportable, 90% in april- sep

Question 7

Rocky Mountain Spotted Fever transmission

Answer 7

Ticks, fleas, mites and lice
20 Ixodid tick species → mostly Demacentor spp.
Transovarial and transstadial

Question 8

Rickettsia exposure

Answer 8

1-3% ticks carry agent
6-20 h of attachment and feeding required

Question 9

Dogs are _______ for the presence of RMSF

Answer 9

Sentinels

Question 10

Rickettsia pathogenesis

Answer 10

On vascular endothelial and smooth muscle cells causing necrotizing vasculitis (escape from phagosome and cytosolic replication by binary fission) → rashes

Question 11

Rickettsia diagnostics

Answer 11

Isolation (BSL 3 contaminent)
Immunofluorescent assay and ELISA
PCR assays (with tick with possible)

Question 12

Rickettsia are sensitive to _________

Answer 12

tetracyclines

Question 13

Coxiella burnetii is the causative agent for ________

Answer 13

Q fever
zoonotic, bioterrorism

Question 14

Coxiella general characteristics

Answer 14

Small pleomorphic rods, intracellular
MZN (modified Ziehl Neelson) stain
Small cell variant (SCV) or vegetative large cell variant (LCV)

Question 15

Coxiella transmission

Answer 15

Aerosol, ingestion
Limited transmission by ticks
Wind-borne over long distances

Question 16

Coxiella survival

Answer 16

Survives in environment for months
Formalin, UV, classical or flash pasteurization, desiccation
0.5% Na hypochlorite

Question 17

Coxiella pathogenesis

Answer 17

Invades vascular endothelium, respiratory and renal epithelia→ multiply in phagosomes and macros

Question 18

Q fever

Answer 18

Febrile, occupational disease
Cattle, sheep, goats= reservoirs

Question 19

Q fever latent infection

Answer 19

Placentitis with abortion or norm delivery → discharge of bacteria
In lactating mammary gland and uterus
Reactivated during parturition

Question 20

C. burnetii diagnostics

Answer 20

Serology and molecular methods
BSL-3 labs permitted to culture

Question 21

C. burnetti disinfection

Answer 21

Ethyl alcohol, chloroform, N-alkyl dimethyl benzyl and ammonium chloride inactivate within 30 mins

Question 22

Ehrlichia and Neorickettsia general characteristics

Answer 22

Obligate intracellular, gram -
Found in granulocytes or monocytes as morulae
Causes acute or chronic disease (vascular disorders)

Question 23

E. canis

Answer 23

Canine monocytic ehrlichiosis (CME)
Vector: brown dog tick (Rhipcephalus sanguineus)

Question 24

E. ewingii

Answer 24

Canine granulocytic ehrlichiosis (CGE)
Vector: Lone star tick (amblyomma americanum)

Question 25

Canine ehrlichiosis

Answer 25

Causes coagulation disorders: petechiae, epistaxis from vasculitis and thrombocytopenia, anemia (pancytopenia)

Question 26

_____________ smear from hosts examined fro morulae for Ehrlichia

Answer 26

Buffy coat

Question 27

Neorickettsia risticci

Answer 27

Cause of Potomac Horse fever (equine monocytic ehrlichiosis- EME)- June to Sep

Question 28

N. risticii pathogenesis

Answer 28

Infects equine monocytes, intestinal epithelium and colonic mast cells

Question 29

N. risticii transmission

Answer 29

Flukes in water Snails and flies intermediate hosts with flie

Question 30

CS for N. risticii

Answer 30

Fever, anorexia, colic, depression, ileus, diarrhea and laminitis

Question 31

Causes of eneterocolitis

Answer 31

Salmonellosis, clostridial colitis, antibiotic-induced colitis, parasites (strongyles)

Question 32

Salmon poisoning in dogs

Answer 32

Caused by N. helminthoeca Reservoir: eating raw fish with fluke* In Northwestern USA

Question 33

Salmon poisoning pathogenesis

Answer 33

Dog releases fluke eggs (fecal) → miracidia infects snail → cercaria infests salmon → dogs eats salmon

Question 34

Salmon poisoning CS

Answer 34

Infects monocytes → fever, anorexia, depression, WL, swollen LNs, hemorragic enteritis

Question 35

Anaplasma

Answer 35

Obligate intracellular A. phagocytophilum* (neutros) A. marginale and centrale of cattle

Question 36

Anaplasma pathogenesis

Answer 36

Tickborne that parasitizes erythrocytes, phagocytes and platelets Membrane-bound morulae in cells

Question 37

A. phagocytophilum distribution

Answer 37

Upper midwest and coastal new england (ixodes scapularis)

Question 38

SNAP 4Dx Plus test by IDEXX

Answer 38

Detects Abs produced by A. phagocytophilum, A. platys, B. burgdorferi, E. canis, E. ewingii Detects heartworm Ag

Question 39

Treatment for anaplasmosis

Answer 39

Doxycycline