Foot and mouth
Highly infectious disease of cattle, sheep, pigs, goats and other cloven hoofed animals
Picorna virus in the genus apthovirus
Very small 20-25 nm
7 major serotypes
Serotype O is most common, within each serotype there are many strains
What are the two types of immunization
Active immunization - the exposure of an unimmunized animal to a pathogen or a vaccine resulting in the creation of antibodies against that pathogen, the animal creates the antibody themselves
Passive immunization - the transfer of preformed antibodies to an unimmunized animal, the antibodies are given to the animal
What are types of killed vaccines
Bacterin -> killed bacteria = histophilus vaccine
Killed virus
Subunit - purified antigens that best cause an immune response
Toxoids - modified toxins from bacteria
What is a modified live vaccine?
Attenuated -> weakened virus that cannot cause disease
viral vector -> a different non-pathogenic virus is engineered to carry genetic material from the problem virus
Avirulent live cultures -> live bacteria that cannot cause disease
What should you not do with endotoxin/antigen stackin
Give more than 2 gram negative containing vaccines at one time
Vaccinate sick or stressed cattle with endotoxin containing products
Use gram negative vaccines in times of heat stress
expose gram negative vaccines to high heat/freezing -> increased endotoxin release
Excessively shake before use
Expose to UV light
How does FMD get transmitted
Direct contact with infected animals
Aerosol spread
Contaminated clothes, farming equipment, bulk milk tankers, contaminated feed
Virus can survive in meat products, sausage, restaurant waste, sewage
Highly infectious - only requires 10-20 virions to infect a cow
What are the types of vaccines
Killed
Modified live
Live - uncommon
others - nucleic acid vaccines, mRNA vaccine
Antitoxins, antivenoms
How do you make a killed vaccine
Grow the pathogen in a laboratory
Kill it with heat or chemicals
What are the advantages of a modified live vaccine
Most closely mimics natural infection
Smaller volume per does
immunologic memory
Longer lived immune response
Can sometimes be used in the face of infection
What is beef quality assurance
Set of guidelines for proper animal handling and treatment to optimize animal health and meat quality
What are the clinical signs of foot and mouth
Incubation period is normally 4-6 days
Onset of clinical signs is very rapid with cows going to apparently normal to severely sick in about 2 hours - depressed, salivating, lame, hunched up, increased temp, severe oral and tongue ulceration
How long does a vaccine last
Duration of immunity - how long a vaccine will offer protection against a given disease
DOI depends alot on the immune system and pathogen
MLV will usually create the strongest immunity
Some vaccines need a yearly booster
if a second vaccine is required, get it
What are the advantages of killed vaccines
No risk of reversion to virulent form
Stability - no mixing requirement, can often be kept in the refrigerator for a period of time after reopening
What are the disadvantages of a modified live vaccine
Careful storage needed, especially after mixing
Careful handling
Must use product within an hour of mixing
cannot keep partially used vial
reversion to virulence possible but rare
Some MLV agents can still cause problems
How do you do proper vaccine handling
Ensure cold chain - transport vaccine in coolers with ice packs
Keep vaccines refrigerated - monitor fridge temps
Do not store vaccines in refrigerators in unheated buildings - dont want to freeze em
Discard any vaccine that freezes or is left out of cold storage
How does FMD affect productivity
Death rate is not particularly high, but disease has a severe effect on productivity - infected animals take a long time to recover, poor milk yields, prolonged lameness, abortions
Young lambs and calves - mortality can be 70%
What are multi-valent vaccines and what are examples
Vaccines against multiple pathogens in one shot
- clostridial vaccines = 3-way, 7-way, 8-way
- respiratory disease = BHV-1, BRSV, PI3, BVD i and ii
- Reproductive = BHV-1, BVD, PI3, BVD i and ii
What are the disadvantages of killed vaccines
Contain lots of antigen
Often needs larger volume per dose
Need two doses to get a really good immune response
yearly boosting may be needed
less robust cell mediated immunity response
some products can really make animals feel sick, go off feed
How do you modify a pathogen
Maybe an existing less virulent form
Grow the pathogen in the lab under abnormal conditions -> most common
Genetic engineering to modify the genetic material of the pathogen
How do you mix a vaccine
Modified live vaccines require mixing - reconstitution of a freeze dried pellet
Always use a sterile transfer needle to reconstitute vaccine - sterile syringe ok
Keep vaccine cool - but not frozen after mixing
how do you control FMD
In endemic areas its controlled by vaccines
Canada, USA and europe - disease is controlled by regulations that prevent entry of animals from endemic countries and contaminated material, most of these countries have an eradication policy
What is endotoxin/antigen stacking
Killed gram negative bacteria vaccines still contain endotoxin - endotoxin is part of the cell wall of gram negative bacteria
Endotoxin present in killed vaccine can be hard on cattle - increased risk of negative vaccine reactions -> cytokine cascade
Giving multiple gram negative vaccines creates an additive effect -> more endotoxin -> endotoxin stacking
What is a variation on the killed vaccine? what does it do?
Toxoid vaccines - some bacteria cause disease by releasing toxins from their cell wall, toxins produced in large quantities in the lab -> purified, Toxin inactivated to produce a vaccine, antibodies are produced to just the toxin
What are the different routes for vaccine admnistration
SC - subcutaneous = most vaccines in cattle
IM - intramuscular = some scours vaccine in cows
IN - intranasal - some BRD vaccines
Oral - in the mouth = some scours vaccines in newborn calves
Intradermal - some swine vaccines
implant - solidbac pinkeye vaccine
What do you not do when mixing a vaccine
Mix more vaccine than you can use in an hour
Shake vigorously to mix
Expose to sunlight
Expose to temps outside the range listed on the label
Allow vaccine to freeze
Put dirty needles into the bottle when refilling a syringe