Pymatuning Carp

http://edis.ifas.ufl.edu/m/#publication?id=VM113

What are the signs of KHV?

Clinical signs of KHV are often non-specific. Mortality may begin very rapidly in infected populations, with deaths starting within 24 to 48 hours after the initial onset of clinical signs. In experimental studies, 82% of fish exposed to the virus at a water temperature of 72°F (22°C) died within the first 15 days (Ronen et al. 2003). KHV infection may produce severe gill lesions which exhibit as gill mottling with red and white patches (Figure 1) (may be similar to columnaris disease signs; SRAC publication #479b on Columnaris Disease). The white patches are due to necrosis (death) of the gill tissue. Gill lesions caused by KHV disease are the most common clinical signs in affected koi. Other external signs of KHV may include bleeding gills, sunken eyes, and pale patches on the skin. Some KHV infected koi may have a notched nose (Goodwin 2012). In some cases, secondary bacterial and parasitic infections may be the most obvious problem, masking the damage caused by the primary viral infection. Microscopic examination of gill biopsies often reveals high numbers of bacteria and various parasites (Hedrick et al. 2000; Haenen et al. 2004).

Internal signs of KHVD are variable and non-specific but may include greater than normal adhesions in the body cavity and enlargement and/or mottled appearance of internal organs (Hedrick et al. 2000; Haenen et al 2004).

Behaviorally, affected fish often remain near the surface, swim lethargically and may exhibit respiratory distress and uncoordinated swimming.