Emergence of Edwardsiella piscicida in farmed channel female, Ictalurus punctatus × Blue male, Ictalurus furcatus, hybrid catfish cultured in Mississippi

Authors: GRIFFIN, MATT - Mississippi State University; REICHLEY, STEPHEN - Clear Springs Foods, Inc; BAUMGARTNER, W - Mississippi State University; AARATTUTHODIYIL, S - Mississippi State University; WARE, CYNTHIA - Mississippi State University; STEADMAN, JAMES - Mississippi State University; LEWIS, MARSHA - Mississippi State University; GAUNT, PATRICIA - Mississippi State University; KHOO, LESTER - Mississippi State University; WISE, DAVID - Mississippi State University

Submitted to: Journal of the World Aquaculture Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/4/2018
Publication Date: 5/11/2018
Citation: Griffin, M., Reichley, S., Baumgartner, W., Aarattuthodiyil, S., Ware, C., Steadman, J., Lewis, M., Gaunt, P., Khoo, L., Wise, D. 2018. Emergence of Edwardsiella piscicida in farmed channel female, Ictalurus punctatus × Blue male, Ictalurus furcatus, hybrid catfish cultured in Mississippi. Journal of the World Aquaculture Society. 50(2):420-432.

Interpretive Summary: This study furthers the research initiated by Griffin et al. (2014) who investigated the molecular identities of presumptive E. piscicida isolates recovered from diseased channel and hybrid catfish in Mississippi and documents gross and histological lesions associated with E. piscicida infections in hybrid catfish. A retrospective survey of archived Edwardsdiella spp. isolates was performed and found that ~90% of all E. piscicida cases submitted to the Aquatic Research and Diagnostic Laboratory in Stoneville, MS, were from channel x blue hybrid catfish. This work supports experimental data suggesting that hybrids are more susceptible to E. piscicida than channel catfish and that E. piscicida is an emerging pathogen of legitimate concern in hybrid catfish aquaculture in the Southeastern United States.

Technical Abstract: There is a trend toward the increased incidence and prevalence of Edwardsiella piscicida septicemia in US catfish aquaculture, particularly in channel ', Ictalurus punctatus, × blue ', I. furcatus, hybrid catfish. From 2013 to 2017, a total of 3242 disease case submissions were made to the Aquatic Research and Diagnostic Laboratory (ARDL) at the Thad Cochran National Warmwater Aquaculture Center in Stoneville, MS. Of these, 1400 (43.2%) were hybrids. E. piscicida was suspected in 138 (4.3%) of cases, the majority of which (89.1%) were from hybrid catfish. A molecular survey of these isolates confirmed the majority (92.0%) to be E. piscicida. Furthermore, cases of E. piscicida from hybrids submitted to the ARDL and the Aquatic Diagnostic Laboratory of the Mississippi State University College of Veterinary Medicine in Starkville, MS, were documented for gross lesions and histological analysis. Grossly, E. piscicida presents with small dermal ulcerations, a raised fluid-filled cranial midline lesion that is frequently ulcerated, hemorrhage in the gills, exophthalmia, and abdominal distension. Internally, lesions include splenomegaly, straw-colored ascites, renomegaly, and occasionally hemorrhagic intestines. Histopathological examination is in agreement with gross observations, and infected fish repeatedly demonstrate a mononuclear meningoencephalitis, hemorrhagic branchitis, splenitis, ulcerative dermatitis, granulomatous interstitial nephritis, and hepatitis coupled with a hemorrhagic enteritis.