FACTORS AFFECTING TRANSMISSION AND SPREAD OF THE VIRUS SPRING VIREMIA OF CARP

Purpose. Spring viremia of carp (SVC) is a viral disease of cyprinids, the causative agent of which is a RNA-containing virus. The virus is represented by one serotype. This disease was firstly described in Yugoslavia by N.Fijan (1968), in Russia ? by N.N. Rudykov (1971). The virus has similar morphology as viruses, which are causative agents of a number of salmonid diseases (VHS, IHN), differing from them by cultural properties. Avirulent strains are among field isolates. Outbreaks of spring viremia of carp are common in carps cultivated in fish farms but they can be observed in fish from different types of water bodies. Manifestations of the disease are related to stress factors. The extensity of infection in unfavorable ecological and zoohygienic conditions can reach 20-40% and is accompanied with the death of the affected fish. The main concern of nowadays is the prevention of the virus penetration into specialized fish farms. The aim of the present study was to conduct the analytical research on factors influencing the transmission and spread of the virus of spring viremia of carp. Methodology. The theoretical basis of the study are the works of foreign and domestic scientists regarding ihtiopathology, including the spread of the virus of spring viremia of carp. The study was conducted using a monographic method and the results of personal analytical observations. Findings. A literature review on the factors that affect the spread of the virus of spring viremia of carp is presented. The factors, which affect the vertical and horizontal transmission of the virus, have been examined. For a long period of time, the geographic range of SVC was limited to European continent that is explained by low water temperatures in the winter. Accordingly, this disease was reported in the majority of European countries. However, in 1998 the disease was registered in Brazil, in 2002 in North Carolina, Wisconsin and Illinois. Outbreaks were reported in Washington and Missouri states in 2004 and in Upper Mississippi in 2007. A SVC-like virus was found in cultivated shrimps in Hawaii. Natural outbreaks of a SVC infection were registered in following cyprinids: common carp (Cyprinus carpio carpio) and koi carp (Cyprinus carpio koi), Crucian carp (Carassius carassius), silver carp (Hypophthalmichthys molitrix), bighead carp (Aristichthys nobilis), grass carp (Ctenopharyngodon idella), Prussian carp (Carassius auratus), ide (Leuciscus idus), tench (Tinca tinca) and bream (Abramis brama). SVCV transmission is horizontal but vertical transmission from the ovarial liquid of carp has been established as well. Among virus transmission vectors are invertebrate parasites Argulus foliaceus (Crustacea, Branchiura) and Piscicola geometra (Annelida, Hirudinea). There is also mechanical transmission of the virus with the aid of fishing gears. The virus can persist in water and silt for a long period of time. Originality. Measures for the prevention of infection of specialized fish farms have been proposed based on the performed analysis. Practical value. The analysis allows developing modern methods of diagnostics and control of the virus spread.