Fish Health and Disease

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

2. Definitions • Epidemiology • 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’sMajor factors affecting disease • Exposure (time) • Virulence/deadliness • Pathogenicity/how contagious it is • Incubation period • Specificity/species fidelity • Ability to use a vector or reservoir • Host behavioral shifts • 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 • 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

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 • 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 • Competition • Food • Space • Mates • Introduced pathogens • Introduced hosts • Spread to native pop’s • Competition with native pop’s • 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 ambhanoi.um.dk • Salmonid farming • Catfish farming • Tilapia • Shrimp Farming • Abalone • Oysters Usfws.gov

19. Salmonids 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 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 • Bacterial disease • Furcunculosis-Aeromonas salmonicida American Fisheries Society T Håstein disease-watch.com

20. Bacterial Infections Salmonids • 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 Redmouth disease Bacterial kidney disease (BKD) Dermal ulcer from Vibrio Rickettsia Photobacterium family infecting gills

21. Viral infections Salmonids • Infectious haematopoietic necrosis (IHN) • Infectious pancreatic necrosis virus

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

23. Ecto-parasites Salmonids • Sea lice

24. Catfish Aquaculture • Bacterial infections in catfish • Aeromonashydrophila • Edwardsiellaictaluri • Aeromonashydrophila • Edwardsiellatarda • Flexibactercolumnaris • Channel catfish virus • Winter kill syndrome – fungal infection • Saprolegnia sp. • Parasites • White spot disease/protozoan - Icthyophthiriusmultifiliis= ich! • Trichodina, Glossatella, Scyphidia and Epistylis and monogeneans • Fish louce, Ergasilussp., Argulussp., Lernaeacyprinacae • “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 • Vibrio sp. • Viral infections • White spot syndrome – Whispovirus • Yellow head syndrome • Protozoan parasites • Milk shrimp syndrome – Agmasomaduorara White spot virus syndrome Cotton/milk shrimp syndrome

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

28. Oysters • Parasitic protozoans • 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