Infectious Dz Flashcards
Dr. Christie’s Lectures
Salmonella enterica causes….
Give me some general info please!
Salmonellosis!
G (-)
Easily transmitted between animals, humans, environment (zoonotic!)
found in 80% of raw chicken fed to animals 20-35% poultry carcasses for human consumption 5-9% raw pet food
CS of Salmonellosis
None to mild severe gastroenteritis
Dx of Salmonellosis
CS fecal culture
Tx of Salmonellosis
Minimal signs/asymptomatic - none Severe cases - isolation, AB’s chloramphenicol, SMZ/TMP, amoxi, ampicillin
Campylobacter general info please!
C. jejuni
G-
Many dogs & cats are asymptomatic carriers
CS of Campylobacter
Large bowel diarrhea
mucous, tenesmus, hematochezia
incr signs w/ STRESS
Dx of Campylobacter
Microscopic exam
Culture
PCR
Tx of Campylobacter
Abs? Unk efficacy
erythromycin, chloramphenicol, cephalosporins, enrofloxacin
Helicobacter
G (-)
Live in stomach
produce high levels of urease to survive low pH
CS of Helicobacter
May or may not cause chronic gastritis
Tx of Helicobacter
Triple therapy
2 antibiotics & antacid
amoxicillin, metronidazole & omeprazole
or
amoxicillin, metroinidazole & famotidine
Brucellosis
B. canis = G (-) aerobic, coccobacillus
cats resistant to infection, only affects dogs
transmmitted through aborted fetal material, semen, urine, milk, orally/conjucntivally?
persists intracellularly
CS of Brucellosis
Dogs can have asymptomatic infections
generalised lymphadenopathy, transient fevers even seizure
Intact males - enlarged scrotum, epididymitis, infertility, testicular atrophy
Females - infertility, abortion, stillborn pups
Other CS: Discospondylitis chorioretinitis, optic neuritis anterior uveitis
Dx of Brucellosis
Serology
titres stapy positive for up to 3 years
Rapid Slide Agglutination Test (RSAT) - good screening (95% sensitive) but not specific due to cross react w/ other bact.
Tube agglutination test (TAT) - titer >200 = active infection, 50-100 = suspect infection
still confirm w/ AGID, ELISA or PCR or bact cult
Culture aborted tissues or blood
Tx of Brucellosis
Very difficult to eradicate
Sterilise all infected animals due to public health concerns
Doxycycline & IM streptomycin - aminolycosides, doxy, quinolones
4 wks tx
retest 6-9 mos post tx
Actinomyces & Nocardia spp
G (+)
Associated w/ anerobic infections, FB migrations, pyothorax, peritonits, bite wounds.
Often has draining tracts/wounds with yellow (sulfer) granules
Associated w/ wounds & pyothorax
Canine Distemper Virus (CDV)
RNA - very susceptible in environment
CDV pathogenesis
water droplets → upper respiratory tract epithelium → multiplies in tissue MØ (<24) → lymphatics
2-4d PI ^^^ viral load in tonsils & retropharyngeal/bronchial LN
4-6d PI virus in lymphoid follicles of spleen, GALT (lamina propria of stomach, SI), mesenteric LN & liver Kupffer cells
^^^ viral replication causes pyrexia & lymphopenia 3-6d PI → 8-9d PI spreads to epithelial tissues & CNS
by 14D PI animals w/ adeq CDV abs & cell-mediated response clear virus from most tissues
Poor immune response leads to spread in skin, exocrine/endocrine glands, & epithelium of GIT, resp tract & GU tract
CS of CDV
Bilateral serous oculonasla discharge
Biphasic pyrexia
KCS
Diarrhea
Vesicles & pustules
Nasal & digital hyperkeratosis & CNS signs “hard pad dz”
tachypnea, coughing
meningeal inflammation
seizures
myoclonus
Dx CDV
3-6 mo unvaccinated (inadequately vxd) puppy
intracytoplasmic distemper inclusion bodies in erythrocytes
MRI
CSF: anti-CDV antibody, ^ protein - if blood contamination of CSF occurs & serology shows CDV +, test for Parvo. If parvo + then confirms + CDV is from vx not dz (CPV isnt neurotrophic)
Serology
PCR: buffy coat, WB, serum or CSF sample
Serum antibody testing - neutralising antibodies “gold standard” (IgG levels)
Indirect FA testing titers
Tx of CDV
Px
supportive care, anti-seizure
POOR
Prev of CDV
Vx
Killed (not in US)
Vector vaccine - canarypox based
MLV (most common)
Can cause vx reactions
Vx schedule - after initial series (6, 9, 12, 16 wks) & 1 yr booster then q 3y
public health risk - Pagets dz?
Canine Adenovirus type 1 (CAV-1)
Highly resistant in environment
PI virus in all tissues but 10-14 d PI virus only in kidneys & excreted in urine 6-9 mos!
Pathogenesis of CAV-1
Severe viremia 4-8d PI
Hepatic parenchymal cells, vascular endothelium & CNS prime targets
ABs form by 7d PI
Acute hepatic necrosis
CS of CAV-1
moribound & die in a few hours post CS onset (fading puppy dz)
Pyrexia
tonsillar enlargement & lymphadenopathy
hemorrhagic diathesis
icterus uncommon
corneal edema & anterior uveitis
Called: Canine infectious hepatitis
Dx of CAV-1
CBC: leukopenia, lymphopenia & neutropenia
thrombocytopenia
Chem: hyperglobinemia day 7-21
^ ALT, AST & ALP
Coagulation abnormalities
UA: proteinuria
abdominal paracentesis/ abdominocentisis: yellow/hemmorhagic fluid
Serology: ^^^ titers after infection
PM pathology: swollen liver & mottled, multiple ecchymotic hemorrhages
Tx of CAV-1
Supportive care for severe hepatopathy
IVF, FFP for albumin & clotting factors, glucose, decr protein diet, laxative & lacutlose to acidify colon (to change ammonia to ammonium)
Prevention of CAV-1
Vx: use MLV for CAV-2 (good cross protection immunity)
Canine Parvovirus (CPV)
DNA virus
requires rapidly dividing cells for replication
CPV-2 (most common)
highly contagious, often fatal, vary stable & resistant in environment
younger predisposed (6wks - 6 mos)
Rottweilers
Incubation period 1-5d
CS of CPV
GIT:
- vomiting, diarrhea (yellow→hemorrhagic), anorexia
- ⇒severe dehydration
- death in 2 days
BM:
severe leukopenia (lymphopenia)
Dx CPV
CS
leukopenia (not all dogs)
fecal ELISA antigen test
fecal PCR
EM of feces
Serology only detect immunity from vaccinated animals
PM pathology: hemorrhagic enteritis, necrosis of crypt epithelium in SI, immunoflourescence
Tx of CPV
Restore fluids & electrolytes
Antiemetic agents - metoclopramide, ondansetron, maropitant (not <10wks, better >16wks)
Food, food, food
gastric protectants
WB, plasma, colloids
Prevention of CPV
Immunity post infection >20 mos
Vx: MLV
DOI: 3-7y
Virus shed for short time (4-5d)
persists in environment >5mos
Canine Coronavirus (CCV)
highly contagious
CS of CCV
enteric CV: subclinical to mild diarrhea
Dx of CCV
EM of fresh feces
Fecal PCR
serum VN & ELISA
CAN JUMP SPP - ZOONOTIC POTENTIAL!
Tx: CCV
Prevention
Supportive
Vx: MLV
Canine Rotavirus
Dx
affects <12 wks old
mild diarrhea
Fecal ELISA for rotavirus antigen
Canine Herpes virus
Pathogenesis
Cytocidal
not very stable in environment
in utero, passage through birth canal & contact w/ litter mates, oronasal secretions from dam
animal <1wk ⇒ fatal generalised infection
animal >2wks ⇒ mild or inapparent infection
repicates in nasopharynx, genital tract, tonsils, retropharyngeal LN, bronchial LN, conjunctival tissue, occas. lungs
can result in abortions/still births
multifocal hemorrhagic necrosis, DIC & thrombocytopenia
CS CHV
Neonates:
Acute death
dull, weight loss, depressed, lose interest in feeding, pass soft stools
petechial hemorrhages
older pups & adults:
mild or inapparant URI
if genital: petechiae, ecchymotic submucosal hemorrhage
vesicles
Dx of CHV
Tx
prevention
viral isolation
serology
PCR - most reliable
Unrewarding in neonates - rapidly fatal
Vx
Rabies virus (RV)
all warm blooded mammals
bite from infected animal
saliva
USA declared canine - rabies free in 2007
Vx still mandatory
prevalence of RV in wildlife increasing
Pathogen of RV
enters peripheral n & ascends sensory or motor fiber
CNS signs develop avg 3-8 wk PI
Cell neccrosis occurs
ascending flaccid paralysis
- to the salivary glands
CS of RV
Prodromal phase (2-3 days)
- Apprehension, nervousness, anxiety, solitude, variable fever
- Fractious animals become very affectionate
Furious/ psychotic type (1-7 days)
- Increase response, bite at objects, photophobic, hyperesthetic
- Restless and roam
Paralytic/ dumb type (1-10 days)
-
Cranial nerve paralysis, hypersalivation, inability to swallow
- Paraparesis, incoordination, terminating in coma and death
Cats sometimes get the paralytic form straight after
the prodromal phase
Dx of RV
Tx
Prevention
CDC
FA testing
Testing of saliva for virus
Serology - used to document rabies immunisation
PCR
NONE
KV Vx
Pseudorabies (PHV-1)
DNA virus
aka Aujesky’s dz, mad itch & infectious bulbar paralysis
USA
contaminated PORK products
ingested & incubation 3-6 d
Ascends nerves
CS of Pseudorabies in SA
Majority dogs develop severe CS
ALWAYS FATAL
self mutilation
trismus, paresis & paralysis of facial mm, difficulty swallowing
aggressiveness, head pressing, convulsions
Cats often die w/o neuro signs
Dx of pseudorabies
Tx
Prevention
CSF : ^^ proteins
Pathology: FA testing for antigen on various tissues (brain, tonsils)
PCR
Futile
keep away from row pork products, vx in endemic areas only
Giardia
Life cycle: excyst w/ help of gastric acid & panreatic enzymes
attach to brush border of villous epithelium - duodenum to ileum (dogs) & jejunum to ileum (cats)
CS of giardia
Diarrhea/maldigestion-malabsorbtion
Dx of giardia
fecal microscopy
identify cysts
fecal ELISA test - antigen in feces
PCR
Tx giardia
Prevention
Fenbendazole 50mg/kg PO SID x 5 d
decontaminate environment
tx affected animals
clean cysts off coats
prevent re-introduction of infection
Cryptosporidium spp
fecal-oral route
Oocytes excyst→ sporozoites→ trophozoites which proliferate on microvillous surface of enterocytes
CS of Cryptosporidium spp
small bowel diarrhea (high vol, low freq) & wt loss
Chronic: tenesmus, hematochezia, abd discomfort
Dx of cryptosporidium
fecal microscopic exam
concentration techniques
cytological & histologic staining
- modified Ziehl-Neelsen stain
immunostaining
fecal antigen detection by ELISA
PCR
intestinal biopsies
Coccidiosis
Isospora spp
asexual & sexual stage
in immunosupressed/young animals
diarrhea (neonates)
anorexia, vomiting, depression
Dx coccidiosis
Tx
fecal flotation
sulfonamides (SMZ/TMP)
Amprolium
Toltrazuril/diclazuril
Neospora caninum
dogs
mostly affects young puppies
CS of Neospora
neurological deficits & muscular abnormalities
puppies < 6mos
ascending paralysis (hind> fore)
dogs > 6mos
multifocal CNS involvement
Dx neospora
Tx
incr. CK, AST
serology:
antibody testing (ELISA, indirect FA, immunoprecipitation)
ck CSF
Trimethoprim sulphonamides 15-20mg/kg BID x 4-8 wks
clindamycin 1-22mg/kg BID 4-8 wks
Leishmania spp
L. infantum
dogs are reservoir hosts for humans/dogs
sand fly
in utero transmission
Pathogen of leishmania
Trojan horse transmission through MØ!
promastigotes from sandfly saliva to skin, phagocytosed by MØ, in which they multiply as amastigotes hidden from immune system, cell is lysed and released, travel through hemolymph regions - blood, LN, liver, spleen, BM & skin
Dx leishmania
NOTIFIABLE CDC!
tissue aspirate (LN 30%, BM 60%)
PCR (most sensitive)
screen blood donors
Serology
IgG levels develop within 2-4 wks
Tx leishmania
difficult
multi drug therapy needed
Hepatozoon spp
Hepatozoon americanum
- Amblyomma maculatum vector
severe dz, southern US
young immunocompromised animals
Hepatozoon canis
Rhipicephalus tick, Amblyomma tick vector
incidental, Africa
Dx H. americanim
Tx
Radiographs - periosteal reaction near mm attachment (good screening test dogs <1 year)
PCR
Blood smear - gametocytes/gamonts in monocytes
NSAIDs for pain
no tx eliminates tissue stage but remission possible
Babesiosis
Hemoprotozoan parasite that infects erythrocytes
Lg. babesia spp: B. canis, B. rossi (most severe), B. vogeli, 2 unnamed
Sm. babesia: B. gibsoni, B. conrdae, B. microti-like, B. caballi, T. annulata, T. equi
Most common in USA B. vogeli (least pathogenic)
Tx of babesiosis - B. vogeli
Usually subclinical but can cause hemolytic anemia
Imidocarb dipropionate - IM repeat in 2wks
B. gibsoni
CS
Dx
50% pitbulls tested in US +
dog fights
CS: hemolytic anemia, thrombocytopenia, vasculitis, fever
Blood smear - cannot distinguish spp on smear
PCR
spleen & liver most affected (filter organ)
Bartonella spp
B. henselae - most common
warm humid area
5-40% cats in US
fleas - Ctenocephalides felis (cat flea)
bacteremia more severe in coinfections w/ FeLV, FIV or FPV
intracellular bacteria in erythrocytes (can be extracellular & in tissues)
CS bartonella
Few develop CS - prdominantlyy subclinical
Lymphadenopathy
Transient fever, lethargy, anorexia
Dx bartonella
Blood culture - reliable for definitive dx
serology -only indicates exposure
PCR - same sensitivity as blood culture
Tx bartonella
Enrofloxacin
Doxycycline
Azithromycin
Prevention bartonella & PH consideration
avoid blood transfusions of cats w/ unk bartonella statue
cat scratch dz - cats ar reservoirs for dz to humans
Mycoplasma spp
hemotropic mycoplasma
- RBCs, G (-),
Mycoplasma haemofelis:
lg form, anemia likely
Candidatus Mycoplasma haemominutum:
sm form (common), rarely causes CS unless concurrent infection or immunosuppression
Transmission of mycoplasma
blood by tranfusion
naturally; arthropod & fleas
horizontal: fighting & saliva
vertical
CS of mycoplasma spp
hemolytic anemia (2 mechanisms)
- immune mediated
- hemolysis: intravascular, extravascular
cyclic parasitemia - sample collected close to capillary bed & immediate smear
Tx mycoplasma
Antibiotics reduce parasitemia but not eliminate organism
Doxy - watch for esophagitis
enrofloxacin - can cause blindness
marbofloxacin
pradofloxacin
prednisolone: to decr erythrophagocytosis in servrly anemic animals
Feline panleukopenia virus (FPV)
feline panleukopenia caused by Fe parvovirus
very stable (>1 yr) in environment
short shedding period
fomites - litter trays, clothing, shoes, hands, food dishes, bedding, infected cages
pathogenesis of FPV
rapidly dividing cells
lymphoid tissue, BM, intestinal mucosa
initial replication oropharynx < 24h PI
plasma- phase viremia 2-7 days - disseminates all over
lymphoid tissue necrosis
intestinal crypt damage
immunosuppression
coinfections common
in utero infection
cerebellar defects, FPV capable of replicating in neurons
Myocarditis & cardiomyopathy
CS of FPV
many subclinical
Peracute - dead <12 hrs
Acute - most common
Dx of FPV
CS & leukopenia
serology - serum VN (if titers rise 4x in paired sample = infection)
fecal viral antigen test - ELISA
viral isolation
PCR (wb, feces, tissues)
Tx FPV
Symptomatic
parenteral fluids/elctrolytes
anti-emetics
covering antibiotics
Food
prevention of FPV
MLV Vx
passive immunotherapy - 2ml from high titer cats to kittens s/c or IP
Other enteric viruses of cats
Canine parvovirus type 2b & 2c: mild disease compared to FPV, tx identical
Feline coronavirus (FeCOV)
Ubiquitous enteric infections
RNA virus
Few that get infected develop FIP - immune-mediated vasculitis
Different strains of FeCOV exist & higher the load more likely FIP occurs
2 serotypes:
Type 1 - unique feline strain (Most common)
Type 2 - recomb of fe & canine coronavirus
Both can cause FIP
Pathogenesis of FeCOV
Virus shed in feces 2 days PI
majority clear virus w/i 2-3 mos
FeCOV & FIP
FeCoV monocytes release:
IL-6, TNF-a, IL-2, Metalloproteinase MMP-9
immune response to FeCoV also plays a role
cell mediatd immune respone - prevents infection
but…
absent CMI & strong humoral response - develops effusive FIP!
intermediate CMI response results in non effusive FIP
CS of FeCoV/FIP
diarrhea (can be severe), upper resp. tract signs
vomiting, wt. loss
predominantly younger cats - takes months to years to develop
multisystemic inflammatory vasculitis dz
FIP misnomer!
Effusive & non-effusive
both forms are same dz, effusive has more damage to bv resulting in fluid & protein accumulation in body cavities
FIP effusive
abdominal distension/ascites
bright or dull
mild pyrexia, wt. loss, dyspnea, tachypnea
pallor/icterus
muffled heart sounds/pericardial effusions
abdominal masses palpable (adhesions & enlarged LN)
FIP non effusive
vague CS
mild pyrexia, wt loss, dullness, depressed appetite
icterus
intraocular lesions:
Iritis
aqueous flare/cloudiness of anterior chamber
keratic precipitates
retinal hemorrhage/detachment
dyspnea/tachypnea
Dx FeCoV/FIP
histopathology demonstrating vasculitis - gold standard
effusion analysis:
^^ protein, modified transudate
alb:glob <0.45
Rivalta test: + result drop retains shape
immunofluorscent staining for FeCov in macrophages - definitive dx!
^^ Alpha 1 acid glycoprotein (high levels aid in dx)
FeCoV antibody titer
RT-PCR - very sensitive, used on effusions (+) is highly suggestive
RT-PCR for mRNA - sensitive & specific but needs specific transport media
Antigen detection in tissues:
immunohistochemistry & direct FA on effusion, cytology (FNA), biopsies
histopathology immunohistochemistry staining is absolute gold standard!
Tx for FeCoV/FIP
Prevention
No real tx exists
glucocorticoids
good nutrition
Vx: Mutant FeCoV strain, IN, produces CMI response
results in AB protection
Vx does not work in cat incubating dz
Husbandry
Feline leukemia virus (FeLV)
- *worldwide**
- *, most dz-related deaths**
more CS
Retrovirus, SSRNA, enveloped
Virus need DNA for replication - so incorporates in hosts own DNA
virus origin FeLV
prevalence
pathogenic: exogenic viruses, FeLV-A, horizontally from cat-cat
non-pathogenic: endogenous virus (inherited), vertical transmission, incr pathogenicity of FeLV-A
FeLV gag (group-associated antegen) gene
Gag protein p27 used as antigen to test for virus
1-8% in free roaming healthy cats
up to 38% if only sick cats included
Transmission of FeLV
close contact
sallive (predominantly) also blood
horizontal spread predominantly
vertical spread - transplacentally or through nursing
readily inactivated in environment
Pathogenesis:
immune status, age of cat
4 stages/types of FeLV infection
Abortive infection:
high levels of neutralizing antibodies
Regressive infection:
effective immune response, initially ELISA FeLV-p27 antigen +, virus cleared in 3-6 wks
FeLV incorporated in genome & can be picked up on PCR
Regressive infections can reactivate in preganancy d/t immunosuppression.
Progressive infection:
Virus not contained
immune system not strong
persistently viremic, often die from FeLV related disease withing 3y
Focal or Atypical infection:
virus restricted to certain tissues
CS of FeLV
hematopoietic malignancy
myelosuppression
infections dz
various co-infections (FIP,FIV), URI, hemotropic mycoplasmosis & stomatitis most common
Fading kitten syndrome
neuropathy
Dx of FeLV
Direct detction of virus:
ELISA, Direct FA testing - look for p27 antigen
Nucleic acid detction:
used when a rgressive infection is suspected in cats with lymphoma or BM suppressive syndrome or chronically inflamed gingival lesions
Antibody detection:
USELESS as cats immune to FeLV have antibodies! Duh!
Tx FeLV
FeLV infected cat
- All cats in household tested
- if some (-) separate, if can’t then vx
- Single cats - confine indoors
Vaccinate w/ core vx (FPV, FHV, FCV) - possible need to vx q 6mos
Tumor tx:
Px worse, routine chemotherapy
Hematological disorders:
most are reversible
Antiviral chemotherapy:
Zidovudine (AZT), didanosine
Feline IFN-ω:
fewer CS & survive longer
Prevention of FeLV
Vx
virus (whole killed virus)
Vaccination does not interfere with testing – unless done within the first few days of vaccination
Does the cat need the vaccination?
Injection site-associated sarcomas
Canarypox vaccine …
Feline immunodeficiency virus (FIV)
Transmission
FIV is a lentivirus, a class of retrovirus
common worldwide (4-24%)
virus in saliva or blood → bites or fights/ wounds
Experimentally all parental routes (i/v, s/c, i/m, i/p)
high concentrations in milk
Transmission from mother to kittens in utero or postpartum is a very rare event
FIV transmission through the mucosal route is rare
Pathogenesis of FIV
Depends on:
Age, younger cats that get FIV develop clinical signs sooner
FIV virus, some isolate are more pathogenic
virus replication tissues rich in lymphocytes (thymus, spleen, ln)
lymphocytes and macrophages in bm, lung, intestinal tract, brain and kidney
After initial viremia – host mounts a clear antibody response
antibodies are detectable 2 to 4 weeks post infection
asymptomatic period
Plasma levels of virus and viral RNA increase from time to time
Affects both CD+4 and CD8+ cells
Disrupts normal immune function
CS of FIV
- Acute phase
- Clinical asymptomatic phase of variable duration
- Terminal phase of infection (feline AIDS)
Dx of FIV
clinicopathology findings: CS non-specific
Antibody testing:
most cats prduce antibodies w/i 60d of exposure
test has high sensitivity
Viral isolation
Repeat ELISA antibody test using another test kit from a different manufacturer
Kittens may have antibodies from their mother up to 6 months of age, these cats should become negative after 6 months
repeat test 60 days after potential exposure
ELISA test can be performed to differentiate FIV vaccinated from FIV cats
ELISA antigen testing
PCR - false (+) possible, PCR not standardised
sensitivity 41-93%
specificity 81-100%
Tx of FIV
Prevention
AZT (zidovudine)
Immunomodulatory tx
IFN-alpha showed a stimulation of immune system
Identify & segregate infected cats
FIV vx
