1. Viral Diseases of Aquaculture Species

2. What is a virus? Does not carry out independent metabolic functions
Can only be seen with an electron microscope
Carries viral genetic material DNA/RNA

3. What is a virus?
Redirects metabolic machinery of host cell to produce more viral DNA/RNA and viral components
Viruses are Obligate intracellular parasites

4. How do you control viruses?
Difficult to treat
Vaccinate using dead or attenuated viruses to illicit immune response
Avoid carrier brood stock
Avoid stress

5. Channel Catfish Virus Disease CCVD
Type of herpesvirus
Primarily affects fish under 6 inches
Sporadic in occurrence but can kill 90+ percent of stock
Host specific to channel catfish
Most common June-Sept.
Most severe in water 85 degrees F

6. CCVD Clinical Signs Fish feed poorly Fish swim erratically
Float head up in water
Dropsy and exopthalmia
Petechial hemorrhages at base of fins
Pale liver, enlarged spleen

7. CCVD Transmission Vertical through gametes
Through water once epizootic has started
Effluent, birds, equipment, etc.

8. CCVD Diagnosis
Suspect ccv when large #’s of fry or fingerlings begin dying above 70 deg. F
Official diagnosis and identification requires special “high tech” lab tests

9. Controlling CCVD No Cure Try to avoid carrier brood stock
No vaccine available
Avoid stress and use BMPs
May use medicated feed to reduce secondary bacterial infections

10. Salmonid viruses IPNV - Infectious Pancreatic Necrosis Virus
affects small salmonids >6”, especially brook trout
VHS - Viral Hemorrhagic Septicemia
primarily rainbow deg F

11. What happens if these occur?
Fish generally destroyed to prevent spread
Sanitize facility

12. Lymphosystis Virus Disease
Most common disease of fish
Occurs in marine, freshwater and ornamental fish
Lesions occur primarily in connective tissue of fins and skin.
Lesions are hypertrophied cells that can enlarge up to 1000x normal size
No cure, but usually not fatal

13. Taura Syndrome (TSV)
first recognized in shrimp farms in Ecuador in 1992 where the disease caused catastrophic losses
spread rapidly to virtually all of the shrimp growing regions of the Americas through shipments of infected post-larvae and brood-stocks
reddening of the tail fan and visible necrosis in the cuticle
has been demonstrated to remain infectious in the feces of sea gulls that have ingested infected shrimp.

14. What is it?
Try to find out why it is
What species it affects
Economic results of this “new” disease