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DefinitionsEpidemiology
The study of the transmission and control of disease
ImmunologyThe study of the components of the
immune system, immunity from disease and the immune response
How to spread diseaseTransmission types
Direct – through contact: high density situations Person to person animal to person - zoonoses mother to child – vertical transmission
Indirect – without contact: density independentRetention on objects/food droplets & particles in air bites and stings
Kissing bug Triatoma sp.
Immune SystemPurpose: Recognize and destroy non-self
cells/particlesNon-self particles = antigens
Innate immune systemImmediate, non-specific responseNo immunological memory/you don’t retain antibody
memory
Adaptive immune systemTime lag between exposure and response, specific
responseExposure leads to immunological memory
±’s ?
±’s ?
Immune ResponseCell-mediated response
Macrophages Natural killer cells /mast cellsAntigen-specific cytotoxic T-lymphocytesand Various cytokines in response to an
antigenHumoral response
Activated antibodies stemming from B lymphocytes
Employs specific cytokines Produces/utilizes memory cellsand Stimulates effector functions of
antibodies
VaccinationInduces adaptive immune system through cell-
mediated and humoral responses Produces memory cells to combat future
exposures
Types of vaccinesDead viral particles are administered – boosters
requiredLow virulence/live viral particles – few to no boostersSubunit vaccination – non-viral protein administered
alone or within a non-harmful virus – sometimes ineffective
Red Queen Hypothesis"It takes all the running you can do, to keep
in the same place.”Constant adaptation among hosts and
pathogens“Building better bugs”Problems with antibioticsProblems with vaccine development
Hygiene hypothesis: Exposure to natural low-level pathogens increases overall immunity
Ways we have circumvented natural immunitySterilizationVaccinationAmplification
Problems with immunity recently developed in humansImmunodeficiencies – inactivity of parts of the immune
systemAuto-immune diseases – immune system attacks itselfHypersensitivity – over-expression of immune response
SUMMARYTo avoid disease you must have limited exposure
both time and density dependantThe type of response depends on previous
exposureInnate or adaptive responseCell-mediated and humoral responses in both types
Vaccines have + and – attributes Specific responseRed Queen hypothesis
Exposure to naturally-occurring antigens can boost immune systemHygiene hypothesis
Pathogens in NatureNot such a bad thing
Typically infections are not virulent when prevalent
Aid in feeding upper trophic levels Remove susceptible individuals from population
Survival of fittest
Link multiple trophic levels within an ecosystemUseful eco-indicators of ecosystem stressors
When epidemics occurCould be a sign of host population structureHave the potential to substantially decrease
host populations
Pathogens in AquacultureNot necessarily a health risk
COOK IT & COOK IT WELL!More likely to economically impact industry by
changingTextureAppearanceTaste
Perception of product is everything = $$Value added products
Top dollar for the most attractive productSingle oysters vs. clustersProper pigments in fish filets
Disease Concerns in Aquaculture
Major concerns for disease epidemics in Extensive Semi-intensive
Intensive
System Design and Pathogen Transmission
Net pen/cage
Semi-closed/Recirculating
Disease transmission
Wastewatertreatment
Permeabilityof containment
Interactionswith native sp.
+ + +
+
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Examples of Diseases in Aquaculture
Salmonid farmingCatfish farmingTilapiaShrimp FarmingAbaloneOysters
ambhanoi.um.dkUsfws.gov
SalmonidsBacterial diseaseFurcunculosis-Aeromonas salmonicida
Salmonids it infectsAtlantic salmon Salmo salar Amago salmon Oncorhynchus rhodurus Brook trout Salvelinus fontinalis Brown trout Salmo trutta m. lacustris Chinook salmon Oncorhynchus tshawytscha Chum salmon Oncorhynchus keta Coho salmon Oncorhynchus kisutch Cutthroat trout Salmo clarki Dolly Varden Salvelinus malma Japanese char Salvelinus leucomaenis Lake trout Salvelinus namaycush Masu salmon Oncorhynchus masou Pink salmon Oncorhynchus gorbuscha Pollan Coregonus pollan Rainbow trout Oncorhynchus mykiss Sea trout Salmo trutta m. trutta Sockeye salmon Oncorhynchus nerka
American Fisheries Society
T Håstein disease-watch.com
Non-salmonid species it infectsAtlantic cod Gadus morhua Sea bream Sparus aurata Turbot Psetta maxima /Scophthalmus maximusAmerican eel Anguilla rostrata Brassy minnow Hybognathus hankinsoni Brook stickleback Culaea inconstans Carp Cyprinus carpio Catfish Silurus glanis Chestnut lamprey Ichthyomyzon castaneum Common shiner Notropis cornutus Creek chub Semotilus atromaculatus European eel Anguilla anguilla Fathead minnow Pimephales promelas Goby Cottus gobio Golden shiner Notemigonus crysoleucas Groper Roccus mississippiensis Lamprey Not specified Minnow Phoxinus phoxinus Mottled sculpin Cottus bairdi Northern pike Esox lucius Paddlefish Polyodon spathula Redbelly dace Chromomus eos Smallmouth bass Micropterus dolomieui Stickleback Gasterosteus aculeatus
Bacterial InfectionsBacterial Kidney Disease – Renibacterium
salmoninarum Enteric septicaemia – Edwardsiella sp.Enteric Redmouth Disease (ERM) – Yersinia
ruckeriPseudotuberculosis – Photobacterium
damsela subsp. piscicida Salmon Rickettsial Disease – Piscirickettsia
salmonis Vibrosis – Vibrio anguillarumHitra disease – Vibrio salmonicida
Salmonids
Rickettsia
Redmouth disease
Bacterial kidney disease (BKD) Photobacterium family infecting gillsDermal ulcer from Vibrio
Viral infections
Infectious haematopoietic necrosis (IHN)Infectious pancreatic necrosis virus
Salmonids
Parasites
Skin & gill fluke Gyrodactylus salarisflatworm
Whirling disease Myxobolus cerebralisprotozoan
Atlantic salmon with Gyrodactylosis
Skull deformation from Myxobolus cerebralis
Salmonids
Darkening of skin from anus to tail
Catfish Aquaculture
Bacterial infections in catfishAeromonas hydrophila Edwardsiella ictaluriAeromonashydrophilaEdwardsiella tardaFlexibacter columnaris
Channel catfish virusWinter kill syndrome – fungal infection
Saprolegnia sp.Parasites
White spot disease/protozoan - Icthyophthirius multifiliis = ich!
Trichodina, Glossatella, Scyphidia and Epistylis and monogeneans
Fish louce, Ergasilus sp., Argulus sp., Lernaea cyprinacae“Brown blood disease”: elevated NO2 in water – not a
pathogen“Broken-skull disease”: lack of ascorbic acid – not a
pathogen
CCV
Ich infection on a catfish
Shrimp farming
Bacterial infectionsVibrio sp.
Viral infectionsWhite spot syndrome – WhispovirusYellow head syndrome
Protozoan parasitesMilk shrimp syndrome – Agmasoma duorara
White spot virus syndrome
Cotton/milk shrimp syndrome
Oysters
Parasitic protozoansMSX – Haplosporidium nelsoni Dermo – Perkinsus marinus
Gastropod predators and parasitesBoonea sp.Urosalpinx sp.
Prevention, Prevention, Prevention!
The ultimate way to stop an outbreak is to prevent it
Prevent stressful situationsProper stocking situationsProper management practicesIdeal water treatment
Prevention measuresVaccinationsStress-treatments (chemical)Anti-bioticsSelective breeding (unintentional &
intentional)Disease-free brood stocksBatch culture/ single batches reared to sizeFungal control of eggs
Intensive systemsControl of multiple environmental factors
SUMMARYMultiple pathogens afflict nearly all farmed speciesPreventative technologies are constantly being
developedGood management and farming practices aid in
successParasites and pathogens are normal parts of
natural ecosystemsEradication = species extinction
= lack of natural community complexityFor the purposes of human sustenance
Limit disease in non-natural stocksBiosecurity
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