Rickettsia, Chlamydia, Coxiella (Ex3)

Question 1

General Features of Rickettsia, Chlamydia, and Coxiella

Answer 1

• highly specialized, obligate intracellular bacteria
• Gram-neg coccobacilli
• susceptible to tetracycline

Question 2

Rickettsia rickettsia

• disease caused
• pathogenesis
• clinical signs

Answer 2

• Rocky Mountain Spotted Fever in humans and dogs
• invades and replicates in endothelial cells of smaller blood vessels, initiating platelet activation, intravascular coagulation, and necrotizing vasculitis
• CS: fever, depression, anorexia, edema, petechiae hemorrhage of mucosa, myalgia, stiff gait

Question 3

Rickettsia felis

• transmission
• disease caused

Answer 3

• transmitted by cat flea
• flea-borne spotted fever in humans
• inapparent infection in cats

Question 4

Rickettsia prowazekii

• disease caused
• hosts

Answer 4

• louse borne rickettsiosis
• humans and flying squirrels
• all domestic animals

Question 5

Rickettsia typhi

• disease caused
• host and vector

Answer 5

• murine typhus

- opossum and flea

Question 6

Orienta tsutsugamushi

• family
• disease caused
• vectors

Answer 6

• Rickettsia
• causes scrub typhus
• chigger mites, rodents, birds

Question 7

General Pathogensis of Rickettsia

Answer 7

• tick transmission
• replication in endothelial cells of small blood vessels
• vasculitis, vasoconstriction
• increased vascular permeability
• hemorrhage, DIC, hypotension, decreased renal perfusion, shock

Question 8

Piscirickettsia salmonis

• hosts
• problem

Answer 8

• in farmed fish

- difficult to control: failure of antibiotics

Question 9

Family Anaplasmataceae

• what are they?
• transmission
• members

Answer 9

• parasites of hematopoietic cells of vertebrate hosts
• transmitted by invertebrate host or a vector
• Anaplasma, Ehrlichia, Neorickettsia

Question 10

Anaplasma phagocytophilum

• habitat
• transmission
• pathology
• clinical signs

Answer 10

• found in neutrophils in the host
• transmitted by Ixodes ticks
• necrotizing small vessel vasculitis
• fever, depression, neutropenia, thrombocytopenia, muscle pain
• horses (subclinical edema, can be fatal) and dogs

Question 11

Anaplasma platys

• disease caused
• pathogenesis
• clinical signs

Answer 11

• infectious cyclic thrombocytopenia
• infects platelets
• often asymptomatic
• fever, uveitis, petechial and ecchymosis

Question 12

Anaplasma marginale

• diseases caused
• transmission
• pathogenesis
• clinical signs
• age susceptible

Answer 12

• causes anaplasmosis in ruminants, and tick fever of cattle (with Babesia)
• transmited via ticks, biting flies, fomites with blood
• targets erythrocytes
• fever, anemia, icterus
• calves more resistant than older cattle

Question 13

Ehrlichia canis

- infections caused and their clinical signs

Answer 13

• brown dog tick borne infection
  Acute: monocytes, platelets
• fever, thrombocytopenia, anemia, vasculitis, lymphadenopathy
  Persistent, subclinical: fever, anemia, thrombocytopenia
  Severe: Tropical Pancytopenia
• weight loss, bleeding, vasculitis, secondary infections

Question 14

Ehrlichia ruminantium

• disease caused
• transmission
• pathogenesis
• clinical signs

Answer 14

• Heart water disease
• reportable
• tick vector: Amblyoma
• replicates in macrophages and endothelial cells
• respiratory and neurological signs

Question 15

Genus: Neorickettsia

• describe the bacteria
• target cells
• transmission

Answer 15

• small intracellular bacteria
• monocytes, macrophages
• trematode vectors

Question 16

Neorickettsia risticii

• disease caused
• transmission
• clinical signs

Answer 16

• Potomac horse fever
• spread by trematodes of brown bats
• aquatic snails as 1st IH, aquatic insects as 2nd IH
• horses drink water infested with flies
• CS: fever, anorexia, leukopenia, diarrhea, laminitis

Question 17

Neorickettsia helminthoeca

• disease caused
• transmission
• pathogenesis (target cells)
• clinical signs

Answer 17

• causes Salmon poisoning in dogs, and Elokomin fluke fever
• IH: snails and flukes
• dogs infected with eat salmon infected with fluke
• infect mononuclear cells
• CS: fever, depression, dehydration, anorexia, vomiting, hemorrhagic diarrhea, lymphadenopathy

Question 18

Chlamydia Unique Features

Answer 18

• dimorphic life cycle:
• reticulate body (intracellular replicating form)
• elementary body (extracellular non-replicating form)
• energy parasites, do not generate ATP

Question 19

What disease is caused by Chlamydia trachomatis?

Answer 19

Human chlamydiosis, an STD

Question 20

Chlamydia psittacis

• diseases caused
• transmission
• signs
• diagnosis

Answer 20

• avian chlamydiosis, ornithosis, or psittacosis
• zoonotic, reportable
• elementary bodies shed by carriers, inhaled into lungs, life cycle in epithelial and phagocytic cells
• septicemic multi-organ infection
• bronchiolitis, bronchopneumonia, fibrinous polyserositis, splenomegaly, hepatomegaly, death
• geimsa stain

Question 21

Chlamydia pecorum

• diseases caused
• signs

Answer 21

• polyarthritis in lambs and calves, stiff lamb disease
• sporadic bovine encephalomyelitis
• locomotor, postural, and behavioral disturbances

Question 22

Chlamydia felis

• disease caused
• signs
• transmission

Answer 22

• feline pneumonitis
• conjunctivitis and rhinitis
• asymptomatic carriers and shedding from reproductive tract

Question 23

Coxiella burnetii

• disease caused
• transmission
• signs

Answer 23

• Q fever
• endospore-like form in environment
• subclinically persists in carrier females
• released around parturition in birth fluids, milk, urine, feces
• spread by inhalation
• usually subclinical, may cause placentitis and abortion in ruminants

Question 24

Q disease

Answer 24

• zoonotic

- flu-like illness, pneumonia, hepatitis, or endocarditis