EPIDEMIOLOGICAL INVESTIGATION AND SURVEILLANCE ANALYSIS OF CARP EDEMA VIRUS SOURCED FROM NORTHERN OF CHINA

In 2017, to further confirm the speculation and epidemiological traits of carp edema virus (CEV), 26 carp farms in 5 provinces of north China, where " acute rot gills disease of carp”, were occurred, surveyed, and sampled. CEV and koi herpes virus (KHV) were detected using quantitative polymerase chain reaction (qPCR) and nested PCR techniques. In addition, 97 carp farms in 9 provinces of China were randomly surveyed for CEV and PCR products for sequencing and analyzing viral DNA of CEV. The results showed that 20 farms were CEV-positive samples, 1 farm was KHV-positive sample, and 1 farm was infected by Sporozoa among 26 farms in north China. Besides, 50 farms were CEV-positive samples among 97 randomly surveyed farms, and infected strains belonged to genogroup II (GII). CEV was detected in different study regions, temperature of water, size of fish, and species of carp with high rate of infection, and there were no significant differences between them. In summary, CEV infection was found to be the major cause of " acute gill-rot disease of carp” in several provinces, and showed high-rate of positive detection in carp farms in north of China. In addition, CEV infection affected various species of common carps including koi carp with different sizes at the temperature range of 12—27℃.