The causative agent in fast-flowing water persists for long (in hours). Its virulence is low, as it usually causes disease in immunocompromised fish spawning. After amplification of their virulence by passaging in the body is weakened fish it causes disease in a large number of fish in the form of epizootic outbreaks.
Ehpizootologicheskaja data. Disease in pikes usually occurs within a few days after spawning (March – April). The most susceptible Mature individuals. The perch, bream, roach and burbot the disease recorded in the summer. The emergence of the disease contributes to cold spring, especially during the spawning period of pike. Then the flash increases and reaches maximum development during the summer months. It fades by the end of summer,
Epizootic process can continue in a large body of water (reservoir, lake) for several years and spread to other reservoirs-current water with transportable or migratory fish. The source of infection are sick and dead fish, microbiological. They are contagious from the beginning falls into the water with secretions, or the decomposition of corpses. Most researchers believe that infection occurs via povrezhdeniya the skin, mucous membranes, intestines. Continue reading