Viral diseases

From Fish
Queen angelfish (Holacanthus ciliaris) infected with lymphocystis. A large pedunculated perioral mass is present that prevents normal feeding

Descriptions of viral diseases of fish are rapidly expanding. Viruses are being reported in new species and interpretation of the significance of findings is also changing. The OIE lists 5 viral diseases of fish as notifiable: epizootic hematopoietic necrosis, infectious hematopoietic necrosis, spring viremia of carp, viral hemorrhagic septicemia, and Oncorhynchus masou virus. In the USA, these diseases should be reported to the USDA. Infectious salmon anemia is not listed as notifiable by the OIE in the 2002 edition of the International Aquatic Animal Health Code; however, it is considered a reportable disease in the USA. Sources for current information on regulatory requirements for aquatic species include the OIE, USDA, state veterinarian offices, state departments of agriculture, and university extension veterinary aquaculture specialists.

While viruses of homeothermic animals are cultured at uniform temperatures, fish viruses have wider, but specific, temperature tolerances in fish cell cultures at lower temperatures. Because of this relatively defined temperature range, variation in temperature may enable control, although often it merely induces latency. Because many viral diseases of fish are geographically limited, regulatory agencies and fish farms in disease-free areas consider them as exotic diseases and require certification of introduced stocks. Many produce high mortality in young fish and little or no losses in adults, which may become carriers. For these reasons, avoidance of carriers and certification of SPF replacement stocks are frequently required. Specific testing procedures are available. Vaccines are not yet commercially available for viral diseases of fish. Drugs are not effective, although antibiotics and other drugs may be used to control secondary bacterial infections that frequently follow viral diseases. Management techniques that minimize stress and crowding, biosecurity measures, and temperature manipulation hold the greatest promise for control of many piscine viral diseases.

  • Herpesviruses
- Channel catfish virus (CCV) disease
- Herpesvirus disease of salmonids
- Herpesvirus disease of turbot
- Oncorhynchus masou virus
- Carp pox
- Infectious hematopoietic necrosis
- Viral hemorrhagic septicemia
- Epizootic hematopoietic necrosis
- Largemouth Bass virus
- Lymphocystis virus
  • Orthomyxoviruses
- Infectious salmon anaemia
  • Miscellaneous