Agency Develops and Licenses New Catfish Vaccine

By Tara Weaver-Missick
March 26, 1999

The first approved modified live fish vaccine has been developed by Agricultural Research Service scientists. The vaccine protects young channel catfish against enteric septicemia (ESC), a major catfish disease that costs farmers as much as $60 million a year in losses. ARS is the U.S. Department of Agriculture’s chief research agency.

Intervet, Inc., Millsboro, Del., has licensed the vaccine, which could be commercially available this spring. This new vaccine, which is a live organism rendered unable to cause disease, will help the catfish industry solve a key problem and will give producers a more cost-effective way to raise healthy fish for consumers.

The vaccine can be used in fish as young as 7 days and up to 31 days after hatching. Seven days is the youngest age at which catfish have been vaccinated to prevent infection. The vaccine can also be given by bath immersion on the truck that takes the young fry to the pond, or in tanks at the hatchery.

ARS has filed for a patent on this new vaccine, which prevents infection caused by the bacterium Edwardsiella ictaluri. ESC is also called “hole in the head,” since it is characterized by lesions and holes in the fish’s cranium, as well as by a bright red color at the base of the gills and belly areas.

Previously, producers had to give antibiotics in feed to control the disease, which isn’t practical because sick fish don’t eat. Also, over time, the ESC bacterium begins to develop resistance to the antibiotics. Molecular biologist Craig A. Shoemaker and microbiologist Phillip H. Klesius, head of ARS’ Fish Diseases and Parasites Research Laboratory, Auburn, Ala., developed the vaccine.

The vaccine should provide lifelong protection. In field studies, it reduced catfish mortality by 80 percent. Enteric septicemia accounts for 70 percent of disease losses in catfish. ESC has never been associated with human infection.

Scientific contact: Phillip H. Klesius or Craig A. Shoemaker, ARS Fish Diseases and Parasites Research Laboratory, Auburn, Ala., phone (334) 887-4526, fax (334) 887-2983, klesiph@vetmed.auburn.edu, cshoemak@acesag.auburn.edu.