Channel catfish virus (CCV) disease

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Channel catfish virus (CCV) disease

Channel catfish virus disease is an acute, virulent herpesvirus infection of fry and fingerling channel catfish that can cause mortality of >80% at water temperatures ≥25°C in small fish (≤5 cm)[1].

As fish age, mortality decreases, and clinical infection in fish >1 yr old is rare. Acute infection often includes a recent history of a stressful event such as handling or transport, low dissolved oxygen, or chemical treatment.

Clinical signs

Infected fish with the disease swim erratically, eventually becoming lethargic, and often hang vertically in the water with their heads near the surface. Infected fish exhibit exophthalmia, haemorrhagic lesions at the base of fins, and haemorrhage and necrosis in the viscera, especially the liver and kidney. Most juvenile channel catfish die within 3 to 10 days of infection with CCV. Fish that survive the disease become latently infected (Gray et al., 1999Down ), a hallmark of herpesvirus infection.

The cell line of choice for virus isolation is channel catfish ovary, followed by serum neutralization to confirm identification. Typical cytopathic effects include cell fusion, syncytia formation, and intranuclear inclusions. There is evidence for vertical transmission of CCV; consequently, survivors of an epizootic should not be used for broodstock.

Although CCV can cause severe mortality when an outbreak is in progress, the annual number of cases of CCV in the catfish industry is relatively low[2].

References

  1. Buck, C. (1990). Channel catfish virus – a review. ATCC Quarterly Newsletter 3:1-2
  2. Merck Veterinary Manual