C19 Gastrointestinal Pathology IV Flashcards
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
