TWENTY-THIRD ANNUAL EASTERN FISH HEALTH WORKSHOP JOHN CARVER INN, PLYMOUTH, MA 30 MARCH - 2 APRIL, 1998 Hafnia alvei, An Emerging Pathogen Of Channel Catfish Andrew E. Goodwin1 and H. Steven Killian2 1University of Arkansas at Pine Bluff, Aquaculture/Fisheries Center, P.O. Box 4912, 1200 N. University Dr., Pine Bluff, AR 71611. 2University of Arkansas at Pine Bluff, Cooperative Extension Program, Chicot County Extension Office, 523 Highway 65 and 82, Lake Village, AR 71653. During the last two winters, moribund channel catfish (Ictalurus punctatus) with unique external lesions have been submitted to the University of Arkansas at Pine Bluff Fish Disease Diagnostic Laboratories. Cases have occurred on commercial fish farms when water temperatures were near 15°C. Most remarkable lesions seen in these cases were severe inflammation around the eyes, bilateral exopthalmia, and red inflamed areas overlying the cranial fontanels. Internal lesions included ascites and red spots on the liver. Fish with these signs continued to die for about 30 days and losses were described by farmers as "moderate" to "severe." Water quality analysis and necropsy of affected fish indicated no serious problems with water chemistry or parasites. Bacterial cultures were taken from liver and brain and plated on TSA with 5% sheep blood. After 24 hours at 22°C, cultures had hundreds of 2-4 mm light gray colonies. The colonies were morphologically similar to Edwardsiella tarda but keyed out as E. ictaluri by the Blue Book Presumptive Identification tables. Further characterization by API 20E produced an excellent identification of the bacterium as Hafnia alvei. This species has not been reported as a pathogen of catfish but has been described in association with septicemia in salmonids (Teshima, C. et al., 1992, Trans. Am. Fish. Soc. 121:599; Gelev, I. et al., 1990, Res. Microbio. 141:573). It is also a recognized pathogen in humans and birds and is part of the normal gut flora in turtles. We have experimentally infected channel catfish fingerlings to test the pathogenicity of H. alvei and to attempt to reproduce the eye and cranial lesions characteristic of the disease. Catfish were challenged at 15 to 20°C using IP injection of 106 or 107 H. alvei per fish, and by immersion in 106 or 107 H. alvei/ml. The higher dose, by injection or bath, produced acute disease that was lethal in 24-48 h, but did not produce the characteristic lesions. Cranial lesions seen in these cases resembled chronic "hole in the head" lesions seen in channel catfish with E. ictaluri infections and probably represented a chronic form of H. alvei infection. Work is currently underway to 1) adjust route and dose to reproduce the chronic form of the disease, 2) fulfill Koch's postulates, and 3) assess the prevalence of H. alvei and H. alvei disease on commercial farms. Return to 23rd Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page