C19 Gastrointestinal Pathology IV Flashcards
(31 cards)
what we need to differentiate vesicular viruses
- Many look clinically and grossly identical
o Need virus isolation or antigen detection to differentiate
vesicular viruses
* Most have multiple serotypes that vary in pathogenicity and virulence
- can we protect against one serotype with a vaccine for another?
- what if you get infected with two serotypes at once?
o Infection or vaccination for one serotype usually does not protect against others o Simultaneous infection with >1 tends to make the problem worse
vesicular viruses
- speed of disease course
- The virus often gets in, wreaks havoc, and gets out very quickly
o An animal may not be shedding virus anymore within days of developing signs
o This is a feature of many viruses, not just vesicular diseases!
Foot and mouth disease
- species?
- genus, family, serotypes
- environmental survival? spread?
- Highly contagious disease of all cloven-hoofed animals, serious economic impact
- Genus Apthovirus, Family Picornaviridae, 7 serotypes
- Virulence and host tropism vary between strains (ex. some are specific to pigs)
<><><><> - Excellent survival in carcasses
- Spread by animal movement, contaminated products
FMD
- pathogenesis
- when does shedding decrease? why?
1) Entry through pharynx, lung
2) Replication in epithelium
3) Dissemination
4) Acute fever, lesions in epithelium prone to mechanical stress
5) By day 11 of clinical disease, shedding decreases due to antibody
FMD
- what type of hosts are pigs, cattle?
Pigs are amplifiers, ruminants can sometimes remain carriers post-infection
FMD
- morbidity, mortality’
- lesions
> how they spread disease
- High morbidity but low mortality – lesions in mouth, on feet, teats
- Profuse salivation in cows
- Vesicles quickly rupture, leaving raw, red ulcers > Secondary infections common
- Vesicle fluid contains lots of virus
- Also exhaled by infected animals
- Interdigital or coronary band lesions present in most animals
- Myocarditis can occur without ulcers in youngstock, sometimes adults
Vesicular stomatitis
- genus, family, serotypes
- how does the virus enter the body?
- pethogenesis?
- length of infection
- temperature & transmission
- Genus Vesiculovirus, Family Rhabdoviridae, RNA virus, multiple serotypes
- Intact epithelium resists infection, but damaged epithelium allows virus in
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1) Replicates at site of inoculation
2) Brief viremia
3) Reaches lymph nodes
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Infection is transient – virus is gone by 6 days
<><> - Absent in cold weather and present when warm – insect vector feeding on lesions?
- Also transmitted by contact
Vesicular stomatitis
- species
- looks like?
- lesions?
- Affects horses, cattle (especially dairy), pigs, some wildlife (deer, rodents, raccoons)
o The only vesicular disease of horses but does not affect small ruminants!
<><> - Identical to foot and mouth disease, economic cost from lost production
<><> - Affected cows may not salivate much
- Mouth lesions > feet (most common in pigs)
Swine vesicular disease
- genus, family
- lesions
- contagious? production impact
- spread
- shedding, carriers
Swine vesicular disease: Genus Enterovirus, Family Picornaviridae
o Lesions mostly on feet (10% in mouth), present in tonsil for 7 days, viremia 2-3 days
o Highly contagious but milder loss of production (impact due to resembling FMD)
o Very resistant to inactivation, spread by contaminated pork and close contact
o May have carrier state with reactivation of shedding under stress
Senecavirus A
- genus, family
- species
- history
Senecavirus A: Genus Senecavirus, Family Picornaviridae
- swine vesicular disease
o Recently described, sporadic outbreaks in Canada and the US
Rinderpest
- genus, family
- species, contagious?
- environmental survival, vaccine
- pathogenesis, shedding
- Genus Morbillivirus, Family Paramyxoviridae, RNA virus
- Highly contagious, acute disease of even-toed ungulates (variable pathogenicity)
- Poor survival outside host – eradicated by vaccination and movement restrictions in 2001
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1) Enter nasopharynx
2) Replicate in tonsils and local LNs (8-11 days incubation)
3) Viremia and fever (lasts 2-3 days)
4) Replication in all lymphoid tissues, mucosa: secretions virus +++
5) No further virus shedding after ~day 9 of clinical disease
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Outbreaks more severe than endemic disease
Rinderpest
- lesions
- signs
- similar to?
- immunity?
- Erosive or hemorrhagic lesions of all mucous membranes, secondary infections common
- Diarrhea +/- blood, abdominal pain, oculonasal discharge, dehydration, emaciation
- Severe intestinal lesions associated with lymphoid tissue
- Similar lesions to BVD mucosal disease and malignant catarrhal fever
- Vaccine or recovery produces permanent immunity
Peste des petits ruminants (PPR)
- genus, family, relative
- course of disease
- species and dead-ends
- immunity?
- leasions
- Genus Morbillivirus, Family Paramyxoviridae, closely related to rinderpest * Similar clinical course and lesions, but more acute and faster course
- Disease in small ruminants, pigs and cattle are dead-end hosts
- Vaccination or recovery cause permanent immunity: target for eradication
<><><><> - Oral necrotic pseudomembranes and secondary infections are common
- Hemorrhagic colitis
- Marked respiratory involvement (cough, dyspnea) Interstitial pneumonia like distemper in dogs
Bluetongue
- genus, familu
- serotypes
- species, presentations
- wildlife
- geography
- spread
Bluetongue: Genus Orbivirus, Family Reoviridae
o Multiple serotypes, not all pathogenic
o Most severe in sheep, goats usually subclinical, disease in cattle rare and mild
o Most North American wild ungulates susceptible except elk and bison
o Sporadic disease in Okanagan valley
* replicate in and spread by Culicoides spp. midges
Epizootic hemorrhagic disease
- serogroup
- species
- disease in sheep
- spread
Epizootic hemorrhagic disease: different serogroup of Orbivirus
o Major pathogen of white-tailed deer
o Mostly subclinical in sheep but can have mild disease
* replicate in and spread by Culicoides spp. midges
Bluetongue and Epizootic hemorrhagic disease
- pathogenesis
- rule outs
Replicates in LNs, spleen
> Viremia 4-6 days post-infection > Infects endothelial cells > Fever, leukopenia
> ~1 week post-infection Microthrombi, increased permeability
> Widespread ischemic necrosis > Edema, hemorrhage, DIC
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Rule outs: contagious ecthyma, photosensitization and vesicular diseases!
Bluetongue and Epizootic hemorrhagic disease
- lesions
- signs
Inapparent to fulminant disease in sheep with bluetongue
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- Hyperemic oronasal mucosa
- Eyelid, ear, lip, and submandibular edema
- Drooling
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- Swelling and hemorrhages of coronet band
- Survivors may be reluctant to move
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- Congested, edematous, cyanotic tongue (hence name)
- Hemorrhages on lips, gums
- Erosion and ulcers of infarcted epithelium
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- May have pulmonary artery hemorrhage, ventricular papillary muscle necrosis +/- pulmonary edema due to heart failure, endothelial damage
Bluetongue and Epizootic hemorrhagic disease in cattle
- sings?
- lesions
- repro issues?
- Rarely clinical in cows, low mortality (if fatal, it’s usually due to secondary infections)
o Fever, anorexia, leukopenia, milk drop
o If lesions form, look similar to sheep
o Can also cause abortion and congenital defects (hydranencephaly, arthrogryposis,
enlarged tongue)
Vesicular disease
- we can’t tell them apart easily
If in doubt……
….report and do virus isolation or antigen retrieval to find out!
Vesicular diseases summary
- which are reportable?
ALL REPORTABLE
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Foot and mouth
Picornavirus
7 serotypes
ruminants
pigs
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Vesicular stomatitis
Rhabdovirus
Multiple serotypes
ruminants (cattle ++)
pigs
horses
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Swine vesicular disease
Enterovirus
pigs
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Rinderpest (eradicated)
Morbillivirus
1 serotype
ruminants (cattle ++)
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Peste des petitis ruminants
Morbillivirus
1 serotype
ruminnats (sheep ++)
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Bluetongue
Orbivirus
Multiple serotypes
ruminants (sheep ++)
horses (mules +)
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Bovine viral diarrhea
- genus, family
- 4 species in genus
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- species
- which virus (1 or 2) more severe
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- mutations
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- immune impact
- Genus Pestivirus, Family Flaviviridae, RNA virus
o 4 species in the genus: BVD-1, BVD-2, classical swine fever, border disease
<><> - BVD is widespread in cattle and can infect most even-toed ungulates
o Range of virulence in both BVD-1 and BVD-2
o BVD-2 often causes more significant external hemorrhage
<><> - Readily mutates via recombination to adapt to host responses
o Can shift from noncytopathic to cytopathic
<><> - BVD suppresses interferon
o Impaired immune function therefore prone to secondary diseases
Bovine viral diarrhea
- pathogenesis
- outcome options
1) Inhaled or ingested
2) Replication in oropharyngeal lymphoid tissues
3) Viremia
4) Outcome depends on status of cow
* Option 1: Immunocompetent, naïve, and nonpregnant or late pregnancy
* Option 2: Immunocompetent, naïve, early pregnancy or pregnant persistently infected (PI) cow
* Option 3: Mucosal disease in PIs
BVDV - naïve, immunocompetent cases
> (including late gestation feti >135 days capable of antibody response)
- signs
- morbidity, mortality
- looks like?
- Subclinical or mild disease in most naïve, immunocompetent cases (including late gestation feti >135 days capable of antibody response)
<><> - Sometimes high morbidity and low mortality syndrome in animals > 6 months
o Fever, leukopenia, lethargy, oculonasal discharge, decreased milk production
o Sometimes mild oral ulcers and diarrhea
<><> - Severe acute BVD causes high morbidity and mortality in all ages o Fever, profuse bloody diarrhea, pneumonia, sudden death
o Sometimes thrombocytopenia
o Resembles rinderpest and mucosal disease of PI animals
