Companion Animal Pathogens Flashcards
List 9 Vector born Bacterial Pathogens
Vector born Bacterial Pathogens
* Rickettsia rickettsia
* Anaplasma phagocytophilum
* Ehrlichia canis
* Neorickettsia helminthoeca
* Mycoplasma hemofelis
* Borrelia burgdorferi
* Bartonella henselae
* Francisella tularensis
* Yersinia pestis
List the 4 main rickettsiales? What are their common features?
Rickettseiales
* Obligate intracellular parasite
* Gram (-) rod
o Anaplasatacae lack part of the cell wall
* Cant culture
* Associated with ticks
Rickettsia rickettsia
Anaplasma phagocytophilum
Ehrlichia canis
Neorickettsia helminthoeca
List the vector, cell preference, host, and disease caused by Rickettsia rickettsia
- Vector: tick (Dermacentor spp.)
o Transmission required minimum attachment of 6-20h
o Nymphs can transmit (transovarial transmission can occur) - Cell preference: endothelium
- Host: dogs/human
- Disease: rocky mountain spotted fever
What is the incubation time and clinical signs of Rickettsia rickettsia
- Incubation: 2-14d
o Fever (most consistent finding)
o Early cutaneous lesions: edema/hyperemia
o Petechia/ecchymoses on MM
o Myalgia/joint pain/swelling
o Neurologic signs
o Necrosis (due to vasculitis)
What are the virulence factors of Rickettsia rickettsia
- Virulence
o Adhesion = outer membrane protein A (attach too receptor of host cell)
o Phospholipase D lyse vacuole inside cell to escape into cytosol
o Cell-cell spread = vasculitis (hallmark)
o Cell mediated immunity = apoptosis oof infected cells = endothelial injury
o = lymphohistiocytic vasculitis
What is the pathogenesis of Rickettsia rickettsia
- Pathogenesis
o Enter via bite f infected tick
o Disseminated in blood
o Invade and replicate in endothelium in small arteries/venules
o Cause vasculitis and perivasculitis
o Increase vascular permeability = edema and DIC
o Hypotension = shock/petechiae/organ damage
Renal failure
CNS damage due to brain edema
How to diagnose Rickettsia rickettsia? What samples?
o Sample: blood/serum/cutanous biopsy
o Test: serology (best) – need 4 fold seroconversion
/IHC/PCR
Not culture (need BSL3 lab)
How to treat Rickettsia rickettsia?
- Tx: doxycycline
List the vector, cell preference, host, and disease caused by Anaplasma phagocytophilum
- Vector: tick (ixodes spp.)
o Need 36-48h of attachment - Cell preference: granulocytes
o Forms membrane-enclosed morulae - Host: dogs
o Also cat/human/ruminant/horse/camelid
o Reservoir: deer/rodent/chipmunk/vole - Disease: tick borne fever
What is the incubation time and clinical signs of Anaplasma phagocytophilum
- Incubation: 14-20d
- Clinically
o Acute fever/lethargy/weak/inappetence
o Generalized lymphadenopathy/splenomegaly
What is the lifecycle/pathogen of Anaplasma phagocytophilum
- Lifecycle
o Attach to P-selectin glycoprotein on neutrophil
o Enter neutrophil via cavaeole mediated endocytosis
o Dysregulate neutrophil function and bypass phagolysosome
o Inhibit superoxide production and neutrophil motility
o Reduce neutrophil transmigration into tissues (more stay in circulation)
List the vector, cell preference, host, and disease caused by Ehrlichia canis
- Vector: ticks (rhiipicephalus/dermacentor – brown dog tick mainly)
- Cell preference: monocyte/macrophage
o Form membrane enclosed morulae - Host: dog
o Reservoir: also canids - Disease: canine monocytic erlichioosis
What is the pathogenesis of Ehrlichia canis
- Pathogenesis
o Mononuclear cells attracted to tick bites
o Carried to LN and escape into circulation
o Localize in ln/spleen/liver
o Replicate in macrophage/monocyte
o Cause lung hemorrhage/epistaxis and vasculitis/thrombocytopenia
What is tthe incubation and clinical signs of Ehrlichia canis
- Incubation: 8 – 20d
o Phase 1: 8-20d = acute
Fever/anorexia/enlarged LN/dyspnea = spontaneously resolve
o Phase 2; 2-4 months = subclinical
Immunocompetent dogs will eliminate infection
o Phase 3: fail to eliminate = chronic
GSD =more severe
Hemorrhage/epistaxis/peripheral edema
Hyphemia/blind/retinal detachment
How to diagnose Ehrlichia canis
- Dx: blood smear + cytology
List the vector, cell preference, host, and disease caused by Neorickettsia helminthoeca
- Vector: liver fluke
- Cell preference: RBC
- Host: dog
o Reservoir: #1 = snails, #2 = freshwater fish (salmon)
o Ingestion of liver fluke from fish
o Very fatal in dogs
o Will shed lots of fluke eggs - Disease: salmon poisoning
What is the incubation period and clinical signs of Neorickettsia helminthoeca
- Incubation: 2-14d (up to 1 month)
- Clinically
o Local granulomatous reaction on GI mucosa
o Peripheral lymphadenopathy
o Fever 5-7d after ingestion
o Diarrhea/v+ after 2 weeks
o Anorexia and wasting
o Death 18d after ingestion
How is Neorickettsia helminthoeca diagnosed (sample? test?)
o Sample: LN aspirate
o Cytology
How are Anaplasmataceae diagnosed (samples? tests?)
Anaplasmataceae
* Sample
o Blood – cytology
o Serum – antibody testing/ELISA
o Aspirate – histo/PCR
o Fecal – feces float
What does the 4Dx SNAP test evaluate for
- 4Dx SNAP ELISA
o Ehrlichia
o Borriella
o Anaplasma
o Dirofilarial
o Should confirm with PCR/serology
How to treat rickettsiales
Rickettsiales
* Tx; doxycycline (mainly)
o Praziquantel (kill flukes)
o Antiemetic
o Fluids
How to prevent rickettsiales
- Control/Prevent
o Remove ticks
o Tick prevention tx
o Prevent from eating rotting carcasses (fish)
List the vector, cell preference, host, and disease caused by Mycoplasma hemofelis
Hemotropic Mycoplasma: feline infectious anemia
Mycoplasma hemofelis
* Vector: ticks/flea
o Oral/bite wounds
* Cell preference: RBC
o Adhere to surface of RBC
* Host: cats mainly (hemocanis – dogs)
What is the pathogenesis of Mycoplasma hemofelis
- Pathogenesis
o Depressions formed by attachment leads to fraaggility of cells
o Macrophages removed from surface of RBC
o Autoimmune rxn – parasite RBC antigen complex = immune mediated osmotic fragility
What are the clinical signs of Mycoplasma hemofelis
- Clinically
o Acute anemia – 2-34d
o Pyrexia
o Latent infection
Sequester in the spleen – reoccur under stress
How to diagnose Mycoplasma hemofelis (samples? tests?)
o Blood – blood smear/cytology
o Confirm with PCR
o No culture
How to treat Mycoplasma hemofelis
- Tx: doxycycline/fluoroquinolones
List the vector, cell preference, host, and disease caused by Borrelia burgdorferi
- Vector: ticks (ixodes pacificus on west and scapularis on east) also flea/lice
- Cell preference: no cell type preference
- Host: Dogs (golden retriever/Bernese)
o Reservoir: rodent/small mammal/deer/birds - Disease: lyme
What are the 3 virulence factors of Borrelia burgdorferi
- Virulence
o Outer surface proteins – adhere in tick
o Surface lipoproteins – stimulate inflammation
o Flagella
What is the lifecycle of the vector that causes lyme
o Can be infected at any point
o Larve > feed
o Overwinter
o Nymph > feed
o Summer = adult
o Die at 2 yo when they lay their eggs
What is the pathogenesis of Borrelia burgdorferi infection
- Pathogenesis
o Adequate attachment time = can transmit bacterium (may be eliminated before clinical disease)
o Bacteria multiply in the skin and enter circulation
o Most circulating organisms killed by phagocytes/complement
o Slow humoral response
o Bacteremia/migration
o Cross endothelium
o Colonize synovial cells and activate IL8 and attract neutrophils
o Neutrophilic polyarthritis = fibrin and fluid accumulate
o Spirochetes can change to spherical forms to protect themselves
What are the clinical signs of Borrelia burgdorferi infection
o No skin rash – usually subclinical
o 2-5 months after exposure
Shifting lameness with painful joints
o 24- 8 weeks post exposure = lyme nephritis
Rare and fatal renal fail
Protein losing nephropathy due to immune complex deposition
V+/peripheral edema/pleural effusion/ascites
How is Borrelia burgdorferi infection diagnosed (sample/tests)
- Dx:
o Blood – antigen capture Elisa but difficult to interpret
o Biopsy of cutaneous lesions
o Synovial sample – fluorescent antibody testing
o PCR
How is Borrelia burgdorferi infection treated
- Tx: doxycycline
o Tx proactively and empirically
List the vector, cell preference, host, and disease caused by Bartonella henselae
- Disease: cat scratch fever
- Host: human/dog
- Vector: flea (also tick/flies/mites/lice/cat bites)
- Cell: macrophage/endothelium/RBC
What are the bacterial features of Bartonella henselae
o Gram (-) aerobe, rod
o Facultative intracellular
o Bind and invade RBC extracellular protein (deformin)
What are the clinical signs of Bartonella henselae
o Fever
o Endocarditis
o Myocarditis
o Granulomatous lymphadenitis
o Cardiac arrhythmia
o Granulomatous rhinitis
o Epistaxis
List the vector, cell preference, host, and disease caused by Francisella tularensis
- Vector: flea/tick (D. variabilis and andersoni, A. americanum)/fly/mosquito
- Cell preference: monocyte/macrophage
- Host: humans
- Disease: tularemia
How is Francisella tularensis transmitted
- Transmit: direct contact with infected or ingestion of infected animals water
o Very infectious
What is the incubation period and clinical signs of Francisella tularensis for cats and dogs
- Incubation : 1-10 d
- Clinically
o Forms: ulcerative/ulceroglandular/ocular/typhoidal/pneumonic
o Cats most susceptible
Hepatomegaly/splenomegaly
Icterus/depression/anorexia
Oral/lingual ulcer
Necrosis
o Dogs: anorexia/low fever/+/- sudden death after contact with infected carcass
Uveitis/conjunctivitis
o Septicemia in susceptible animals = DIC/SIRS/multiorgan dysfunction syndrome
What are the bacterial features of Yersinia pestis
- Gram (-) coccobacillus
List the vector, cell preference, host, and disease caused by Yersinia pestis
- Host: cat/human
o Reservoir: rodents - Vector: flea
o Als direct contact/ingestion of infected/cat bites - Cell: mononuclear cells
What is the incubation period and clinical signs of Yersinia pestis
- Incubation: 1-7d
- Clinically
o Bubonic = LN infect
o Pneumonic = pneumonia/fever/cough
o Systemic = septicemia
o Cat = early signs are fever/lymphadenopathy/ocular discharge
Bacteremia = bacteria in saliva
What are the common lesions of Yersinia pestis
o Necrotizing lymphadenitis
o Lot of petechiae
o Abscess
o Lingual ulcer/cutaneous disease
How is tularemia and the plague diagnosed? (sample/tests)
- Sample: be careful! (very infectious)
o Swab from wound/ulcer
o Tissue/whole body
o Blood - Test
o IHC
o Serology
o PCR
How is tularemia and the plague treated?
- Tx: gentamicin/doxycycline/enrofloxacin
How is tularemia and the plague prevented?
- Prevent: reduce arthropod exposure/limit exposure to dead reservoir hosts
List the 3 common tick types of western CA? + common names
- Western CA
o Dermacentor andersoni: rocky mountain wood tick
o Dermacentor variabilis: American dog tick
o Rhipicephalus sanguineus: brown dog tick
List the 3 common tick types of eastern CA? + common names
- East CA
o Ixodes pacificus: western black legged tick
o Ixodes scapularis: black legged deer tick
o Ambylomma americanum: lone star tick
