TWENTY-FOURTH ANNUAL EASTERN FISH HEALTH WORKSHOP Royal Pavilion Resort, Atlantic Beach, NC MARCH 9-11, 1999 Epizootic Mycobacteriosis In Chesapeake Bay Striped Bass Wolfgang K. Vogelbein, D.E. Zwerner, H. Kator, M. Rhodes and J. Cardinal Department of Environmental Sciences, Virginia Institute of Marine Science, The College of William and Mary, Gloucester Point, Virginia 23062 USA The striped bass, Morone saxatilis is highly prized by recreational and commercial fishermen of Chesapeake Bay. During the past two years, the Aquatic Animal Disease Diagnostic Lab (AADDL) at VIMS has received numerous cases of striped bass exhibiting a prominent ulcerative dermatitis. This condition appears widespread in Virginia waters with lesion prevalence approaching 30-50% in certain tributaries. Histopathologic evaluation of the skin ulcers and visceral organs such as spleen, kidney and heart indicated the occurrence of prominent granulomatous inflammation. Skin ulcers rarely penetrated into underlying muscle tissue. Ziehl Neelsen staining of histologic sections confirmed the presence of acid-fast bacilli within granulomas. Bacteriological evaluations of granulomatous skin and splenic tissues confirmed the presence of acid-fast organisms belonging to the genus Mycobacterium. To date, we have isolated and identified multiple species from affected fish including M. marinum, M. peregrinum, M. scrofulaceum, M. gordonae and M. terrae complex. Possible additional species have been presumptively identified and efforts to definitively characterize these isolates continues. Several of these species are human pathogens. Because of the great popularity of the striped bass as a sports fish and because the skin ulcers usually harbor mycobacteria, the potential for contact between anglers and this infectious agent is high. A study is now underway to 1) understand the relationship between this new disease and possible stressors such as environmental degradation or loss of forage base and starvation of striped bass stocks, 2) elucidate prevalence and spatial and temporal distribution of the disease in Virginia waters, 3) clarify disease pathogenesis, and 4) determine the potential human health risks associated with increased exposure to these pathogenic organisms. This study is funded by the Virginia Marine Resources Commission Project RF98-2. Return to 24th Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page