TWENTY-THIRD ANNUAL EASTERN FISH HEALTH WORKSHOP JOHN CARVER INN, PLYMOUTH, MA 30 MARCH - 2 APRIL, 1998 Microbiological Findings From The "Pfiesteria Outbreak" In The Chesapeake Bay In 1997. Ana Baya Fish Health Unit, Animal Health Diagnostic Lab, College Park, MD Striped bass: All fish, except controls, had small to large shallow skin ulcers, but not all fish had the same internal lesions. Some fish had Mycobacterial infections. Gross lesions consisted of small (0.5-3 mm diameter) greyish-white nodules in the spleen, head-kidney, liver, heart, and gonads. Affected spleens were at least twice the normal size, and frequently contained the largest nodules. Mycobacterium spp was isolated from the internal organs. Some fish had Streptococcosis. Grossly, some of these fish had corneal opacity and meningitis. A non hemolytic Streptococcus type IIb was isolated from the internal organs. Photobacterium damsela was isolated from one fish. Internally this fish appeared very different from the ones showing signs of Mycobacterial or Streptococcus diseases. Internal organs of this bass were totally covered by a white scummy fibrinous opaque fluid. Edwarsiella tarda was isolated from 3 fish. All fish had large numbers of the parasite Pomphorrhyncus bulbocolli in the intestine. Several papers associate a relationship between Mycobacterium and large numbers of parasites due to the debility and physiological stress within affected fish. Bacteria were not isolated from fish without sores taken from the same site as the disease fish nor did they shows any internal abnormalities or large number of parasites. In menhaden cases, bacteria most frequently isolated from the skin lesions or internal organs of these fish were: Aeromonas hydrophila, Vibrio cholera non 01, and Pseudomonas fluorescens. It should be noted that all three of these bacteria have been reported to be of zoonotic significance, in that they will produce disease in humans as well as in fish. Other bacteria found in samples: Klebsiella oxytoca, Plesiomonas shigelloides, Alcaligenes faecalis, Proteus vulgaris, Vibrio parahaemolyticus, Vibrio vulnificus.   Return to 23rd Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page