TWENTY-SECOND ANNUAL EASTERN FISH HEALTH WORKSHOP ROYAL PAVILLION RESORT, ATLANTIC BEACH, NC MARCH 18 - 20, 1997 Management of Streptococcal infections in hybrid striped bass and tilapia John P. Hawke Department of Veterinary Microbiology and Parasitology, Louisiana State University, School of Veterinary Medicine, Baton Rouge, LA 70803 Streptococcal infections caused by a variety of phenotypes have been diagnosed in a number of fish species by the Louisiana Aquatic Animal Disease Diagnostic Laboratory, however, three species predominate. Streptococcus iniae is the most common species isolated from diseased tilapia reared in intensive systems. Both S. iniae and Enterococcus faecalis/faecium have been isolated from hybrid striped bass cultured in intensive systems. Group B type Ib Streptococcus sp. strains commonly cause infections in hybrid striped bass reared in marine and brackish water environments on the gulf coast. Management strategies for streptococcal infections vary according to the species of streptococcus, whether the bacterium is considered to be a facultative or obligate pathogen, and the culture system utilized. Strategies can be separated into the following categories: 1. Prevention and/or avoidance; 2. Improvements in water quality; 3. Water sterilization treatment 4. Therapy with antimicrobial agents; 5. Vaccination; and 6. Destruction of fish stocks, decontamination, and restocking closed recirculating systems.Future research on management of streptococcal infections proposed by various groups include: basic epidemiological studies of S. iniae infections in tilapia, genetic analysis of strains of S. iniae from human and fish sources, models for pathogenesis in various fish species, virulence factors, carrier detection, vaccines and immune response, genetic selection for disease resistance and production of disease resistant transgenic fish. Return to 22nd Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page