Viral Diseases of Viral Diseases of Aquaculture Species Aquaculture Species

What is a virus?What is a virus?

Does not carry out independent Does not carry out independent metabolic functionsmetabolic functions

Can only be seen with an electron Can only be seen with an electron microscopemicroscope

Carries viral genetic material Carries viral genetic material DNA/RNADNA/RNA

What is a virus?What is a virus?

Redirects metabolic machinery of Redirects metabolic machinery of host cell to produce more viral host cell to produce more viral DNA/RNA and viral componentsDNA/RNA and viral components

Viruses are Viruses are ObligateObligate intracellular intracellular parasitesparasites

How do you control How do you control viruses?viruses?

Difficult to treatDifficult to treat Vaccinate using dead or Vaccinate using dead or

attenuated viruses to illicit attenuated viruses to illicit immune responseimmune response

Avoid carrier brood stockAvoid carrier brood stock Avoid stressAvoid stress

Channel Catfish Virus Channel Catfish Virus DiseaseDiseaseCCVDCCVD

Type of herpesvirusType of herpesvirus Primarily affects fish under 6 inchesPrimarily affects fish under 6 inches Sporadic in occurrence but can kill Sporadic in occurrence but can kill

90+ percent of stock90+ percent of stock Host specific to channel catfishHost specific to channel catfish Most common June-Sept. Most common June-Sept. Most severe in water 85 degrees FMost severe in water 85 degrees F

CCVD Clinical SignsCCVD Clinical Signs

Fish feed poorlyFish feed poorly Fish swim erraticallyFish swim erratically Float head up in waterFloat head up in water Dropsy and exopthalmiaDropsy and exopthalmia Petechial hemorrhages at base of Petechial hemorrhages at base of

finsfins Pale liver, enlarged spleenPale liver, enlarged spleen

CCVD TransmissionCCVD Transmission

Vertical through gametesVertical through gametes

Through water once epizootic has Through water once epizootic has startedstarted

Effluent, birds, equipment, etc.Effluent, birds, equipment, etc.

CCVD DiagnosisCCVD Diagnosis

Suspect ccv when large #’s of fry Suspect ccv when large #’s of fry or fingerlings begin dying above 70 or fingerlings begin dying above 70 deg. Fdeg. F

Official diagnosis and identification Official diagnosis and identification requires special “high tech” lab requires special “high tech” lab teststests

Controlling CCVDControlling CCVD

No CureNo Cure Try to avoid carrier brood stockTry to avoid carrier brood stock No vaccine availableNo vaccine available Avoid stress and use BMPsAvoid stress and use BMPs May use medicated feed to reduce May use medicated feed to reduce

secondary bacterial infectionssecondary bacterial infections

Salmonid virusesSalmonid viruses

IPNV - Infectious Pancreatic IPNV - Infectious Pancreatic Necrosis VirusNecrosis Virus– affects small salmonids >6”, affects small salmonids >6”,

especially brook troutespecially brook trout

VHS - Viral Hemorrhagic VHS - Viral Hemorrhagic SepticemiaSepticemia– primarily rainbow trout @ 59-66 deg Fprimarily rainbow trout @ 59-66 deg F

What happens if these What happens if these occur?occur?

Fish generally destroyed to Fish generally destroyed to prevent spreadprevent spread

Sanitize facilitySanitize facility

Lymphosystis Virus Lymphosystis Virus DiseaseDisease

Most common disease of fishMost common disease of fish Occurs in marine, freshwater and Occurs in marine, freshwater and

ornamental fishornamental fish Lesions occur primarily in connective Lesions occur primarily in connective

tissue of fins and skin. tissue of fins and skin. Lesions are hypertrophied cells that Lesions are hypertrophied cells that

can enlarge up to 1000x normal sizecan enlarge up to 1000x normal size No cure, but usually not fatalNo cure, but usually not fatal

Taura Syndrome (TSV)Taura Syndrome (TSV)

first recognized in shrimp farms in Ecuador in 1992 first recognized in shrimp farms in Ecuador in 1992 where the disease caused catastrophic losses where the disease caused catastrophic losses

spread rapidly to virtually all of the shrimp growing spread rapidly to virtually all of the shrimp growing regions of the Americas through shipments of regions of the Americas through shipments of infected post-larvae and brood-stocksinfected post-larvae and brood-stocks

reddening of the tail fan and visible necrosis in the reddening of the tail fan and visible necrosis in the cuticle cuticle

has been demonstrated to remain infectious in the has been demonstrated to remain infectious in the feces of sea gulls that have ingestedfeces of sea gulls that have ingested infected infected shrimp.shrimp.

What is it?What is it? Try to find out why it isTry to find out why it is What species it affectsWhat species it affects Economic results of this “new” Economic results of this “new”

diseasedisease