TWENTY-SECOND ANNUAL EASTERN FISH HEALTH WORKSHOP ROYAL PAVILLION RESORT, ATLANTIC BEACH, NC MARCH 18 - 20, 1997 Bacterial pathogens associated with eggs of Atlantic salmon Rocco C. Cipriano USGS/Biological Resources Division, National Fish Health Research Laboratory, 1700 Leetown Road, Kearneysville, WV 25430 Eggs from Atlantic salmon (Salmo salar) were examined to determine the efficiency of iodophor disinfection for Aeromonas salmonicida, cause of furunculosis, and to test the hypothesis that Flavobacterium psychrophilum, cause of cold-water disease, can be vertically transmitted. Twenty matings were made with Atlantic salmon held at the Richard Cronin National Salmon Station (Sunderland, MA). Fertilized eggs were placed in 50 ppm iodine for 30 min, and water hardened for 60 min. Eggs were iced and shipped to the White River National Fish Hatchery (Bethel, VT), again disinfected in 100 ppm iodine for 10 min, and placed in Heath incubators receiving UV-treated well water. Although A. salmonicida was cultured from 12 of 20 egg lots before disinfection, the pathogen was not recovered after the initial disinfection (50 ppm/30 min). Before additional studies were conducted, eggs were again disinfected in 100 ppm iodine for 60 min. Flavobacterium psychrophilum was present among 9 lots pre-disinfection and pathogen concentrations ranged between 5.0x103 to 5.5x107 cfu/g of egg. Even after three disinfections, the pathogen was still cultured from 5 of these lots at concentrations between 7.1x102 to 6.1x107 cfu/g of egg. Isolates tested were directly suspended in and killed by a single incubation with 100 ppm iodine for 30 min. These results indicate that iodophor disinfection of eggs for A. salmonicida was complete and highly efficient. However, F. psychrophilum was still recovered from eggs even after a total of three disinfections; one in 100 ppm iodine for 60 min, a concentration of iodophor that effectively killed the pathogen on direct contact in half the time. Data strongly indicate that F. psychrophilum can be vertically transmitted via intra-ovum infection. Return to 22nd Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page