Spring viremia of carp

from Wikipedia, the free encyclopedia

The spring viraemia of carp (Engl. Spring viremia of carp , SVC ) is a virus-induced, acute running, highly contagious disease of carp . It occurs mainly when the water temperature rises in spring and affects carp of all ages. It can cause high losses. The spring viremia of carp is the acute form in the complex of infectious ascites (IBW), the chronic form is bacterial. The disease is notifiable in Germany and Switzerland.

Pathogen and disease development

The pathogen is the Rhabdovirus carpio (RVC) or Spring Viremia of Carp Virus (SVCV). It is a single-stranded RNA virus that belongs to the rhabdovirus family as an unclassified vesiculovirus .

The gills are suspected to be the main entry point . Transmission is also possible through contact as well as via the fish egg and blood-sucking parasites ( carp louse ). The incubation time is seven days at 13 ° C water temperature and can increase to 60 days at higher temperatures. The morbidity also depends strongly on the water temperature.

After infection, the virus spreads via the blood ( viraemia ) and colonizes internal organs. The virus is excreted in the faeces. Surviving fish remain virus carriers for life.

Clinical picture

The SVC shows all the typical signs of septicemia in fish such as uncoordinated swimming movements, shortness of breath , darkening, eyeball prolapse and bleeding in the skin, the gills, the base of the fins and the eyes. In addition, ascites causes the abdomen to swell and the anus to protrude. Long strands of feces (so-called "pseudo-faeces") are released when the faeces are released.

Diagnosis

The distended abdomen in particular enables a suspected clinical diagnosis.

The pathological examination reveals blood-serous exudate in the body cavity, edema and punctiform bleeding of the internal organs. The intestine is inflamed and contains yellow, slimy contents. Pathohistologically, there is fibrinous peritonitis and local bleeding.

The diagnosis can only be ensured by the pathogen detection. During viraemia, it is possible to grow the pathogen in fish cell cultures from the blood, later from the internal organs. The virus neutralization test or the direct immunofluorescence test can be used to detect viruses .

The chronic form of infectious ascites and inflammation of the swim bladder can be excluded from the differential diagnosis .

Combat

Specific therapy is not possible. If the disease breaks out, the process can be stopped by increasing the water temperature. A vaccine that is ready for practice does not exist.

The fight against SVC is aimed at building free stocks by stocking SVC-free juvenile fish and disinfecting the eggs of suspect animals with organic iodine preparations. As possible vectors, parasites must also be combated through hygiene measures.

source