Part 1: Epidemiology and Immunity Fish Health and Disease

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

Epidemiology- disease within pop’s Major 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

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

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.

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 ?

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

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

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

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

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

Part 2: Diseases in Aquaculture Fish Health and Disease

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

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

Disease Concerns in Aquaculture Major concerns for disease epidemics in ExtensiveSemi-intensiveIntensive Why? Crowding Competition Food Space Mates Introduced pathogens Introduced hosts Spread to native pop’s Competition with native pop’s Water conditions

Requirements for Disease All 3 must be present for an outbreak

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

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

Salmonids Bacterial disease Furcunculosis-Aeromonas salmonicida 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 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 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 Salmonids Rickettsia Redmouth disease Bacterial kidney disease (BKD) Photobacterium family infecting gills Dermal ulcer from Vibrio

Viral infections Infectious haematopoietic necrosis (IHN) Infectious pancreatic necrosis virus Salmonids

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

Ecto-parasites Sea lice Salmonids

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 CCV Ich infection on a catfish

Tilapia Bacterial disease Streptococcosis Legions on bulging eyes

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

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

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

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

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

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