Disease control in animals for PH Flashcards
Infections can be controlled by interventions that act in which 2 ways?
Prevent or reduce transmission
Reduces susceptible population
How can transmission be reduced/prevented? Give an example of each
Prevent contact between the infected and susceptible individuals - biosecurity
Remove infected individuals - culling
Reduce ability to transmit - vaccinate
How can the susceptible population be reduced? Give examples
Improve immunity e.g. vaccination
Make individuals harder to infect e.g. probiotics
Remove a susceptible population e.g. culling
What are the 2 serovars for Salmonella enterica?
S. enterica serovar Typhimurium
S. enterica serovar Enteritidis
What hosts does salmonella infect?
Any
Mainly poultry for S.enterica serovar Enteritidis
What hosts do Camplyobacter bacteria mainly affect? (LA)
+++ Poultry (C. jejuni)
+ Pigs (c.coli)
+ Ruminants
What hosts does E.coli affect? (LA)
+++Cattle
+Ruminants
How are Salmonella, Campylobacter and Escherichia coli transmitted in a herd/flock?
Faecal shedding
Oral/faecal route
Salmonella enterica serovar Enteritidis also has another tranmission route except faecal/oral. What is this?
Vertical transfer
To eggs
What are the main colonisation sites for Salmonella, Campylobacter and E.coli?
Lower intestinal tract (most)
Caeca (chickens)
What disease does salmonella cause? What does this depend on?
None, diarrhoea or invasive systemic disease
Reproductive tract infection (Salmonella serovar Enteritidis)
Host and isolate
What does campylobacter cause? (LA)
None to mild/moderate D+
What does E.coli cause?(LA)
None - adults as commensal
D+ in calves
How is Salmonella entered into the food chain?
Contamination of meat by gut in abattoir
Contamination of meat in animal lifetime
Faecal contamination of eggs
Transomarian infection of eggs (S. eneteria serovar Enteritidis)
How is Campylobacter entered into the food chain?
Contamination of meat by gut during abbatoir
Liver infection
How is E.coli entered into the food chain?
Contamination of meat from guts or hide
Contamination of crops by infected manure
Do Salmonella, Campylobacter and E.coli have specific legislation for control?
Salmonella - yes
Others - no
How are these bacteria controlled on farms?
Vaccination
Surveillance
Biosecurity and hygeine
Probiotics (Salmonella only)
What has been the biggest cause of the fall in Salmonella levels?
Vaccination
other factors - hygiene/biosecurity, probiotics, heat treatment of feed
What is the Lion Mark Scheme? What year did it come into action?
Voluntary Scheme of hygiene, biosecurity standards and routine surveillance
1998
What does current Salmonella surveillance require for broiler chickens going to slaughter or layer chickens?
2 swabs per flock
Within 3wks of slaughter/regularly for layers
What happens if layers test positive for Salmonella?
Eggs can’t be class A
How does the Salmonella vaccine work?
Inject killed bacteria then live bacteria into water
Which poultry are not able to receive the Salmonella vaccine?
Broilers
Biosecurity works well for Salmonella. Give examples of biosecurity
Vehicle wheel wash
Concrete around buildings
Specific equipment and clothing between houses
Vermin proof
Why do biosecurity failures allow campylobacter?
More transmissible than others (Salmonella)
Transmissible via fomites
Campylobacter can also be due to thinning. What is this?
Overstocked birds
Then depopulated and moved to another farm
Why is it so important for equipment in slaughter house to be clean?
High production speed
200 animals minute - fast cross contamination
What parts of the body does campylobacter infect in poultry?
Caeca
Liver
Muscle
Why may animals with disease be culled?
Welfare reasons
Prevent disease transmission
Why is preventing stress important for preventing transmission of disease?
Stress increases faecal shedding
Reduces immune function
What is competitive exclusion?
Give microflora to animals that promote gut health and inhibit pathogens
What care can be taken in slaughter houses to reduce disease?
Avoid gut/faecal contamination
Carefully remove GI tract (difficult as fast production)
Why are antibiotics not given anymore?
AMR
What can be given in livestock as a therapeutic treatment of disease? What are the problems of this?
Bacteriophages - viruses that infect bacteria
Resistance may develop, host specific range
What post-slaughter control of meat can reduce disease?
Rapid chilling/steaming
Wash in chlorinated water
UV treatment
Bacteriophage treatment
