1. Fish Health and Disease
Part 1: Epidemiology and Immunity

2. Definitions Epidemiology Immunology
The study of the transmission and control of disease
Immunology
The study of the components of the immune system, immunity from disease and the immune response 

3. Epidemiology- disease within pop’s Major factors affecting disease
Exposure (time)
Specificity/species fidelity
Virulence/deadliness
Ability to use a vector or reservoir
Pathogenicity/how contagious it is
Host behavioral shifts
Incubation period
Host response type/immune

4. Disease = Opportunity & Condition
All 3 are required for disease to proliferate

5. How to spread disease Transmission types
Direct – through contact: high density situations
Person to person
animal to person - zoonoses
mother to child – vertical transmission
Indirect – without contact: density independent
Retention on objects/food
droplets & particles in air
bites and stings
Kissing bug Triatoma sp.

6. Immune System
Purpose: Recognize and destroy non-self cells/particles
Non-self particles = antigens
Innate immune system
Immediate, non-specific response
No immunological memory/you don’t retain antibody memory
Adaptive immune system
Time lag between exposure and response, specific response
Exposure leads to immunological memory
±’s ?
±’s ?

7. Immune Response Cell-mediated response Humoral response Macrophages
Natural killer cells /mast cells
Antigen-specific cytotoxic T-lymphocytes
and Various cytokines in response to an antigen
Humoral response
Activated antibodies stemming from B lymphocytes
Employs specific cytokines
Produces/utilizes memory cells
and Stimulates effector functions of antibodies
Effector functions of antibody (protein binding molecule that changes the function of a protein), which include pathogen and toxin neutralization, classical compliment activation, and opsonin promotion of phagocytosis and pathogen elimination

8. Vaccination
Induces adaptive immune system through cell-mediated and humoral responses
Produces memory cells to combat future exposures
Types of vaccines
Dead viral particles are administered – boosters required
Low virulence/live viral particles – few to no boosters
Subunit vaccination – non-viral protein administered alone or within a non-harmful virus – sometimes ineffective

9. 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 antibiotics
Problems with vaccine development

10. Hygiene hypothesis: Exposure to natural low-level pathogens increases overall immunity
Ways we have circumvented natural immunity
Sterilization
Vaccination
Amplification
Problems with immunity recently developed in humans
Immunodeficiencies – inactivity of parts of the immune system
Auto-immune diseases – immune system attacks itself
Hypersensitivity – over-expression of immune response

11. SUMMARY To avoid disease you must have limited exposure
both time and density dependant
The type of response depends on previous exposure
Innate or adaptive response
Cell-mediated and humoral responses in both types
Vaccines have + and – attributes
Specific response
Red Queen hypothesis
Exposure to naturally-occurring antigens can boost immune system
Hygiene hypothesis

12. Fish Health and Disease
Part 2: Diseases in Aquaculture

13. Pathogens in Nature Not such a bad thing When epidemics occur
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 ecosystem
Useful eco-indicators of ecosystem stressors
When epidemics occur
Could be a sign of host population structure
Have the potential to substantially decrease host populations

14. Pathogens in Aquaculture
Not necessarily a health risk
COOK IT & COOK IT WELL!
More likely to economically impact industry by changing
Texture
Appearance
Taste
Perception of product is everything = $$
Value added products
Top dollar for the most attractive product
Single oysters vs. clusters
Proper pigments in fish filets

15. Disease Concerns in Aquaculture
Major concerns for disease epidemics in
Extensive Semi-intensive Intensive
Why?
Crowding
Introduced pathogens
Competition
Introduced hosts
Food
Spread to native pop’s
Space
Competition with native pop’s
Mates
Water conditions

16. Requirements for Disease
All 3 must be present for an outbreak

17. System Design and Pathogen Transmission
Net pen/cage Semi-closed/ Recirculating - + + + - - - +
Disease
transmission
Permeability
of containment
Interactions
with native sp.
Wastewater
treatment

18. Examples of Diseases in Aquaculture
Usfws.gov
Salmonid farming
Catfish farming
Tilapia
Shrimp Farming
Abalone
Oysters
ambhanoi.um.dk

19. Salmonids Bacterial disease Furcunculosis-Aeromonas salmonicida
Non-salmonid species it infects
Atlantic cod   Gadus morhua
Sea bream   Sparus aurata
Turbot   Psetta maxima /Scophthalmus maximus
American 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
Salmonids it infects
Atlantic 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

20. Bacterial Infections Salmonids
Redmouth disease
Salmonids
Bacterial Infections
Bacterial Kidney Disease – Renibacterium salmoninarum
Enteric septicaemia – Edwardsiella sp.
Enteric Redmouth Disease (ERM) – Yersinia ruckeri
Pseudotuberculosis – Photobacterium damsela subsp. piscicida
Salmon Rickettsial Disease – Piscirickettsia salmonis
Vibrosis – Vibrio anguillarum
Hitra disease – Vibrio salmonicida
Rickettsia
Rikketsia- kidney is swollen and spleen is enlarged
Photobacterium family infecting gills
Bacterial kidney disease (BKD)
Dermal ulcer from Vibrio

21. Viral infections Salmonids Infectious haematopoietic necrosis (IHN)
Infectious pancreatic necrosis virus
Hemorrhaging of gills and expansion of stomach region

22. Parasites Salmonids Skin & gill fluke Gyrodactylus salaris
flatworm
Whirling disease Myxobolus cerebralis
protozoan
Skull deformation from Myxobolus cerebralis
Atlantic salmon with Gyrodactylosis
Darkening of skin from anus to tail

23. Salmonids
Ecto-parasites
Sea lice

24. Catfish Aquaculture Bacterial infections in catfish
Aeromonas hydrophila
Edwardsiella ictaluri
Aeromonashydrophila
Edwardsiella tarda
Flexibacter columnaris
Channel catfish virus
Winter 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
Ich infection on a catfish
CCV

25. Tilapia
Bacterial disease
Streptococcosis
Legions on bulging eyes

26. Shrimp farming Bacterial infections Viral infections
White spot virus syndrome
Shrimp farming
Bacterial infections
Vibrio sp.
Viral infections
White spot syndrome – Whispovirus
Yellow head syndrome
Protozoan parasites
Milk shrimp syndrome – Agmasoma duorara
Cotton/milk shrimp syndrome

27. Abalone Abalone Virus Ganglioneuritis (AVG)
Herpes-like virus that originated from farmed cultures

28. Oysters Parasitic protozoans Gastropod predators and parasites
MSX – Haplosporidium nelsoni
Dermo – Perkinsus marinus
Gastropod predators and parasites
Boonea sp.
Urosalpinx sp.

29. Prevention, Prevention, Prevention!
The ultimate way to stop an outbreak is to prevent it
Prevent stressful situations
Proper stocking situations
Proper management practices
Ideal water treatment

30. Prevention measures Vaccinations Stress-treatments (chemical)
Anti-biotics
Selective breeding (unintentional & intentional)
Disease-free brood stocks
Batch culture/ single batches reared to size
Fungal control of eggs
Intensive systems
Control of multiple environmental factors

31. SUMMARY Multiple pathogens afflict nearly all farmed species
Preventative technologies are constantly being developed
Good management and farming practices aid in success
Parasites and pathogens are normal parts of natural ecosystems
Eradication = species extinction
= lack of natural community complexity
For the purposes of human sustenance
Limit disease in non-natural stocks
Biosecurity