Unit 3 - Swine Viral and Vesicular Diseases Flashcards
What are the two major exotic viral diseases posing a threat to the swine industry in the US?
Hog cholera
African Swine Fever
What are Hog cholera and ASF characterized by?
High fever
Lymphoid involvement
High mortality
Skin erythemas to effusions
What is the etiologic agent of hog cholera?
Pestivirus
Where has hog cholera been eliminated from?
The US, Canada, and several European countries
What are the hosts of hog cholera?
Domestic swine and wild boar
How is hog cholera transmitted?
Direct contact via the oro-nasal route
Garbage feeding
Personnel, equipment, pets, birds, and arthropods
Where is the primary site of invasion for hog cholera? Viremia and spread to where?
Primary site of invasion is the tonsillar crypt with viremia and spread to the lymphoid tissues.
How long is the incubation period for hog cholera?
2-4 days
What clinical signs are associated with hog cholera?
High fever
Excitable at first followed by apathy and anorexia
Marked ocular discharge: severe conjunctivitis
Hind leg incoordination, huddling, diarrhea, dyspnea, recumbency with paddling
Congenital tremors in piglets with cerebellar hypoplasia
Morbidity and mortality for hog cholera is ____ with survival only ____-____days PI. In subacute HC, pigs
show less severe signs of disease and succumb within ___ days. In chronic disease, pigs may
survive ____ days or more.
100%
10-20
30
100
What cells does hog cholera target?
Endothelial cells
What lesions are associated with hog cholera?
Disseminated petechiae and ecchymoses especially in the skin, larynx, bladder, brain, and kidney (turkey-egg kidney). Multifocal infarcts of the margin of the spleen are characteristic but inconstant. Button ulcers (because of infarcts) of the colon. Lymphopenia
How is hog cholera diagnosed?
PCR on the tonsil
FA on tissues
SN test: Best in the chronic forms
Virus isolation
T/F: Hog cholera is not reportable, but ASF is.
False - Hog cholera is… I assume ASF would be too but it hasn’t been in the US
What ddx should be considered with hog cholera?
ASF, salmonellosis, erysipelas
What is the etiologic agent of ASF?
Asfarvirus
What animals serve as reservoirs for ASF?
Wart hogs, giant forest hogs, and bush pigs in Africa
T/F: Asfarvirus survives for prolonged periods under most environmental conditions especially when protected in meat or blood.
True
T/F: All secretions and excretions from acutely ASF infected domestic pigs are infectious
True
How is ASF transmitted?
Ticks or hematophagous insects
Introduction of infected swine or indirectly through contaminated personnel and equipment.
How long is the incubation period for ASF?
1-4 days
What clinical signs are associated with ASF?
Fever: 105 - 108 F
Hyperemia of the skin
Abortions
Mortality in 100% of virulent forms
What is the pathogenesis of ASF?
Enters via mouth or URT and spreads to tonsils then spreads quickly to the mandibular lymph nodes and throughout the body via blood and lymph.
When injected (tick bites) the virus spreads rapidly to the RES and lymphocytes.
What gross lesions are associated with ASF?
Severely hemorrhagic and edematous lymph nodes (look like hematomas, often with little
discernable lymphoid tissue).
Splenomegaly
Petechial hemorrhages throughout the body.
Kidneys may be very hemorrhagic.
How is ASF diagnosed?
PCR assay
Clinical signs and lesions
How is ASF controlled?
Slaughter all infected and exposed swine
Restrict swine and pork movement
Thorough cooking of garbage before feeding it to swine
What is foot AND mouth disease?
A vesicular disease affecting cloven-hoofed animals including wild and domestic ruminants
and swine.
T/F: FMD has the broadest host range of the vesicular diseases affecting domestic animals and is the most easily transmitted
True
T/F: In addition to cloven-hoffed animals, elephants, hedgehogs, horses, and even humans have been infected with FMD.
FALSE BITCH FALSE!!!! HORSEYS CANNOT GET FMD
T/F: FMD is said to be one of the most economically important worldwide when one includes the adverse effects on trade.
True
What is the etiologic agent of FMD?
Aphthovirus (picornavirus)
How are the majority of FMD cases transmitted?
transmission is thought to be through infected saliva
During the early febrile period what contains the FMD virus?
All tissues, excretions and secretions contain the virus including semen
FMD does not survive long in muscle tissue. Why?
Because of the acidic environment, but it will survive in bone marrow and in organ meats.
Following an outbreak and total depopulation of all the animals on a farm, the FMD virus disappears fairly rapidly except from where?
protected dark, moist areas
In cattle, what is FMD characterized by?
Depression, elevated temperature, and the appearance of vesicles containing a clear fluid on the epithelium of the mouth, tongue, muzzle, interdigital space, tops of the claws, teats and sometimes the surface of the udder
The vesicles are prone to rupture
Following rupture, large whitish flaps of epithelium may be found partially covering the
affected areas
What occurs 24-48 hours after the formation of vesicles due to FMD?
Virus enters the blood and multiplies in various organs.
The heart muscle of calves is particularly affected by some strains of FMD. What lesion is associated with this?
Myocardial necrosis (yellowish streaks are found) - cause of high mortality
What clinical signs are associated with FMD in cattle?
Affected cattle become lame and champ their jaws and drool because of the mouth lesions.
Most lose condition rapidly
The claws may be totally undermined and eventually sloughed
Mastitis in lactating dairy cattle can be a major cause of economic loss
What clinical signs are associated with FMD in swine?
Disease in swine is generally similar to that in cattle.
Pigs develop lameness initially as the most conspicuous sign.
Large vesicles may appear on the snout and other epithelial surfaces.
How is FMD diagnosed?
Clinical signs
Competitive ELISA
RT_PCR
How is FMD controlled during an outbreak?
REPORT
Aggressive quarantine measures need to be instituted immediately for several miles around affected farms - no livestock can move, other animals (pets) need to stay put, humans are confined
All affected animals and all animals that have had contact with them are slaughtered and buried on the farm with quick-lime
Non-contact cattl,e sheep, and swine can be immunized with a DIVA vaccine and tested before being released from quarantine
In areas where FMD is enzootic, what is the choice method of control?
Vaccination
T/F: Vesicular exanthema of swine is grossly indistinguishable from FMD.
True
What is the etiologic agent of vesicular exanthema?
Calicivirus.
What clinical signs are associated with vesicular exanthema?
12 hours prior to vesicular formation - fever, off feed
Vesicles of varying size appear on the lips, tongue, snout, footpads and the skin between the claws, coronary band, dew claws, and teats of nursing sows
The vesicles rupture easily, leaving a raw surface often with flaps of whitish skin attached.
The animals can become quite lame and will refuse to rise when prodded and may walk knuckled over on
their fetlocks or knees
rapid and extensive weight loss
Why is there high mortality associated with vesicular exanthema in neonates?
due to the development of lesions in the oral and nasal cavities that may cause suffocation or from
starvation because of agalactia in the sows.
How is vesicular exanthema prevented/controlled?
Because of the similarity of the infection to FMD, depopulation is required
No feeding of raw garbage
What is the etiologic agent of Swine Vesicular Disease?
enterovirus that is closely related to the Coxsackie B5
What lesions are associated with Swine Vesicular Disease?
Indistinguishable from other vesicular diseases.
Morbidity in natural outbreaks has been reported at 25 to 65%.
A mild non-suppurative meningoencephalitis throughout the CNS was observed in both natural and experimental disease.
How is Swine Vesicular Disease controlled and prevented?
Cooking all garbage or no garbage feeding
Strict quarantine and slaughter of all affected and exposed swine
What is the etiologic agent of vesicular stomatitis?
Vesicular stomatitis virus (VSV), a rhabdovirus
What is vesicular stomatitis?
Cause of fever and vesicular and ulcerative lesions primarily in horses, cattle and swine.
What is the most virulent serotype of VSV?
The New Jersey serotype
FYI - the other serotype is the Indiana
Where, geographically, does vesicular stomatitis occur?
Disease occurs only in the Western Hemisphere and is more prevalent in tropical and subtropical areas.
How is vesicular stomatitis transmitted? When?
Flies are thought to be the major vector but the virus also spreads by contact.
Late summer
What lesions are associated with VSV in horses and cattle?
Oral lesions are more common than lesions on the feet
The lesions may appear as blanched areas with little or no vesiculation.
Even when vesicles are present on the
oral mucosa, they rupture rapidly and leave raw denuded ulcers
What clinical signs are associated with VSV in horses and cattle?
Drooling, teeth grinding, lip smacking and rubbing affected areas are most commonly observed.
Lactating cattle experience a sudden drop in milk production and develop lesions on the teats that can be quite extensive and severe.
In VSV infected animals, lameness characterized by hyperemia and ulceration of the coronary band are most common in ______and _______.
horses
swine
The disease course of VSV is usually only __-___ days and most animals recover without complications. Lesions usually heal with __-__ weeks. Persistent lameness can occur due to damage to the _____ ____?
3-4 days
2-3 weeks
coronary band
T/F: VSV is zoonotic
True - humans are susceptible and can develop a fever and vesicles
How is VSV diagnosed?
Notification of state or federal authorities is essential as with all vesicular diseases
Demonstration of viral antigen in tissues
Paired serum samples for antibody titers.
Virus isolation and identification
How is VSV controlled/prevented?
Fly control and control of other vector insects
Quarantine of affected premises until three weeks after all clinical signs disappear.
What does Senecavirus A cause?
Vesicular lesions similar to FMD
Senecavirus A can be recovered from the ____ and _____ for 1 – 3 weeks following onset of
clinical signs but viral RNA can be detected by ____ in serum and oral fluids for 4 weeks beyond resolution of the lesions.
tonsil
feces
PCR
T/F: Senecavirus A is zoonotic
False - humans do not appear to be infected by the virus
What clinical signs are associated with Senecavirus A?
Pigs may have a transient and mild loss of appetite and lameness.
There may be low fever in some pigs
Low to high morbidity
Essentially 0% mortality
What lesions are associated with Senecavirus A?
Vesicular lesions
There are no other lesions that can be related directly to the virus
How is Senecavirus A diagnosed?
PCR
How is Senecavirus A prevented and controlled?
Quarantine and diagnostic procedures need to be followed the same as any other vesicular disease.
Virus is inactivated by bleach but it needs to have
contact for 15 minutes or so.
What are the etiologic agents of Agalactia syndrome of sows?
Physiologic factors - hormone impalances Coliform mastitis Vitamin E - Se deficiency Toxemia Mycotoxins Hypocalcemia and ketosis
What clinical signs are associated with coliform mastitis?
High fever (105-107F) in early acute stages (may decline as chronicity increases)
The mammary glands are swollen, hyperemic and have a pitting type edema.
Milk flow is markedly reduced, and may be coming only from unaffected portions of the gland
Inappetence
Constipation
What may be a contributing factor to development of coliform mastitis in sows?
Inappetence
What clinical signs are associated with metritis?
Excess vaginal discharge (lochia) but this varies a lot between normal sows. If the discharge is purulent or bloody, there is probably an infection.
Detection of agalactia requires knowledge of what?
normal nursing behavior
Normally, during the first
__- __ hours after birth the piglets sleep and nurse at irregular intervals. After this, nursing occurs
every ___ to ___ minutes.
12-24
40-60
What are the 5 phases to normal piglet nursing?
- Jostling for position on the udder.
- Nosing the udder with vigorous up and down movements of the head.
- The quiet phase during which piglets suck on the teats with slow mouth movements (about 1 per second).
- Suckling with rapid mouth movements (about 3 per second). Milk can be expressed only during this short time.
- A brief return to sucking with slow mouth movements and nosing the udder.
What is a good indication that pigs are not getting enough milk?
Pigs are squealing a lot, are continuously trying to nurse and drink water from the sows’ watering cup
What clinical signs are associated with piglets that are not getting enough milk?
The pigs progressively lose weight and eventually become lethargic, pile up in a warm area, become emaciated, and die. Death generally occurs between 2 and 5 days of age due to hypoglycemia, diarrhea and being overlain by the sow.
Necropsy of piglets that died due to starvation reveals what?
Dehydration, emaciation, empty stomachs and serous atrophy of body fat.
How is coliform mastitis diagnosed?
Clinical signs
Culture - possible but difficult
Rule out other causes
How is coliform mastitis prevented?
maintain good sanitation in the farrowing unit
Vitamin E, Selenium supplementation may be useful
How is coliform mastitis treated?
It is currently thought that most cases will resolve on their own.
Antimicrobials may be of some use.
NSAIDS
