diseases_infectiondynamics&biosecurity Flashcards
what are the 4 disease categories?
genetic
environmental
nutrional disorder
infectious disease
what are reasons for infectious diseases?
parasites
fungal infection
bacteria
viruses
what is the health triangle ?
relationship between:
- host
- infectious agent
- environment
name 2 parasites infectious diseases
salmon louse
aemobic gill disease
what is pathogenicity?
p. refers to the ability of an organism to cause disease.
what is virulence?
v. refers to the degree of pathology caused by the pathogen.
often correlates with the pathogens ability to multiply within the host.
name 2 fungal infections/mycoses
crayfish plague
saprolegnia spec
name 2 bacteria transferred infectious diseases
vibriosis
cold water vibriosis
winter ulcers
furunculosis
name 2 viral transferred infectious diseases
PD: pancreas disease
ISA: infectious salmon anemia
IPN: infectious pancreatic necrosis
Pox virus –> gill infection
reovirus –> heart and skeletal muscle inflammation
describe vibriosis and cold water vibriosis.
- what is the main and only difference ?
marine: - atlantic salmon and rainbow trout
- control : vaccination
- widespread distribution in marine water
difference:
- water temp.:
cold water vibriosis –> low water temp.
vibriosis –> high water temperatures
what is the treatment against bacterial diseases ?
vaccination
what are the three most common viral diseases for salmonids?
ISA(infectious salmon anemia),
pancreas disease (PD),
IPN (infectiuos panceratic necrosis)
what are bacterial disease characteristics?
- reservoir= widespread in water
- farm populations
- pathogenicity at an infectiuos dose
- water temperatures, stress
viral diseases charcteristics?
- reservoir= infected farmed fish
- farm populations
- pathogenicity is host specific
- water temp. and stress
there are legislations about health status of ….
of country/regin of origin ("disease free")
of population (mandatory health control)there are only international health legislations. true or false?
false, international and national
who/what regulates the helath status?
name a few
-OIE: world animal helath orgainzation
- the trade and disese regulation
the pancrease disease regulations
- the aquaculture management regulation
there are three list, in which disease are chategorized.
chategroized based on what?
and on which of these lists can you find :
-furunculosis
-PD
-ISA
1=exotic
2=nonexotic
3=national list
ISA= nonexotic–> 2
PD and furunculosis –>3
what are the two control strategies?
- live with infection
2. keep the infection out
what is the managemnet strategy, if a disease is introudced?
- immediate remval of infected population
- cleaning and desinfection
- fallowing (stilllegen)of the site
how can becterial diseases be treated?
antbiotics
how can sea lice be treated ?
cleaner fish, mechanical methods, pharmaceuticals
what are the three vaccination methods?
oral
immersion
injection (mannually/automatically)
what are the vacine methods/types?
5
- inactivated-killed
- adjuvants injection
- subunit vaccines(–> create wek immune response)
- live vaccines (–>immune response)
- DNA vaccines
at what lifetime of the production cycle are salmons vaccinated?
when they are smolts in the freshwater, before they get transportetd to the farm (or at the farm in sea water)
what is RPS?- what does it describe?
RPS = (1- %deaths in vacinnated fish/%deaths in unvaccinated fish) *100
=relative percent survival
– >describes the vaccine impact= vaccine efficacy
what does RPS= 90 mean?
high efficacy of the vaccine
what does RPS=40
mean?
low efficacy of the vaccine
the use of antibitics is close to zero since 1995, and the fish production rapidly in increases since then.
true or false?
true, due to vaccines
what are the species that still have the highest antbiotic prescription?
- atlnatic salmon
- marine species (altnatic cod, turbot, halibut)
- other species: including cleaner fish -lumpfish
how is the vaccine protection against PD ad IPN ISA?
PD=moderate
IPN= unknown
ISA=unknown
what are the effects of fish vaccination?
-does NOT prevent pathogen introduction
BUT: reduces risk for outbreak in the populat.
-reduces spread of diesase within the far//to other farms/to wild fish
-R0<1
what is R0?
=basic reprodution number
–> =number of secondary cases arising from a single primary case
what is when R0 > 1?
each primary case wll produce more tha one secondary case –> epidemic
what is when R0 < 1?
the infection will tend to die out
what effect has vaccination on R0?
vaccination reduces the number of susceptible hosts –> R0 <1
what does herd immunity mean?
even non-vaccinated individuals and poor-responders are protected through the immunity of the herd/population
on what does the herd immunity depends on?
- depends on the proportion of immune individuals + vaccine efficacy + infection pressure
what is “biosecurity”
/”biosecurity plans”?
= preventive methods to reduce the risk of transmission of infectious diesase.
if the disease is introduced –> do control measures to reduce consequences/losses
- reduce the risk of further spread
what does “bio-exlusion” mean?
prevent disease introduction
what are the biosecurity levels ?
4
- internationally
- nationally regionally
- area/zone
- production unit
what are source for pathogen introduction?
- biological material (e.g.smolt, eggs )
- wild fish
- feed
- water
vectore: eqipment, transport, vehicles etc.
what are generell important elements of biosecurity plans?
- mandatory health control of fish
- suveillance
- transport of stocking population -> standard, regulatins
- water source–> hygienic quality
- “all in-all out” (one generation –> one stocking and harvesting –> cleaning and disinfection etc.)
what are imprtant elements of biosecurity plans on the farm?
- hygiene barries btween clean and un clena area
- limited contact to other sites/populations
- own staff, own eqiupment and operations
- control of visitors
- controll of feed and equipment
What does the PD regulation fro 2017 say?
- norway divided into 4 zone (2 PD free zone, 2 surveillance zones (western/mid-norway)))
- testing 20 fishes/each month all farms
- vaccination mandatory in buffer zone (mid norway)
what are control measures within PD-zone?
- coordinated production
-seperated fish generations
fallowing of sites
-distance betw. sites
-control with transport
-surveillance testing
vaccination
how long does a zoneneed to be disease free that it can be declared as PD free zone?
10 years
how does vaccination against PD effects a PD zone?
- mortality
- growth/day
- discarded at slaughter
mortality rate sinks
growth rate ≈unchanged
discarded at slaughter = halve
is PD transmitt over long distance easier/harder than ISA transmitt?
relative risk higher or lower?
easiere –> relative risk is higher
