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Joint project aims to combat enteric septicemia in basa catfish

VIET NAM - Scientists from RMIT University are teaming up with Vietnamese experts in Melbourne, Australia to develop a vaccine for Edwardsiella ictaluri bacteria and so increase the profitability of basa catfish farming in Vietnam.

Professor Peter Coloe of RMIT University and Vietnamese PhD candidate Phan Ngoc Thuy are working on fish specimens collected in Vinh Long and Can Tho to immunize fish from Edwardsiella ictaluri, the causative agent of enteric septicemia, a systemic disease caused by pathogenic organisms or their toxins in the bloodstream.

Cole and Thuy intend to develop a product that would be administered by immersing fingerlings in water containing the vaccine, and then placing the fish in ponds for protection through harvest.

The research strategy centers on creating a strain of the bacteria that can penetrate the fish and induce immunity, but cannot infect the fish.

The best vaccine will comprise live Edwardsiella ictaluri, which stimulate all types of immunity, and will thus give the fish longer protection than a vaccine composed of dead bacteria.

Coloe said this approach is an established method in the development of veterinary vaccines. The same research procedure is being used in the effort to inoculate chickens from salmonella bacteria - another RMIT project.

The head of Applied Sciences at RMIT University said the university wishes to help young scientists from Vietnam solve problems that challenge farmers and fish producers.

"Aquaculture is a critical element of Vietnam's globalization program at the macro level, and the welfare of tens of thousands of households at the micro level is influenced by successful productivity at the farm level," Coloe said.

Coloe and Thuy believe that the over-population of fish farms can contribute to the spread of the bacteria. They compared two separate ponds, stocking 90 and 30 fish per cubic meter, respectively, and measured feeding patterns in both.

Thuy said that in the pond with 90 fish per cubic meter, water quality dropped, nutrient conversion efficacies decreased and there was a greater likelihood of fish succumbing to disease.