June 27, 2007

Vietnam, Australia join hands to combat enteric septicaemia in catfish

Experts from Vietnam and from Royal Melbourne Institute of Technology (RMIT) University have teamed up to develop a vaccine for Edwardsiella ictaluri bacteria to increase the profitability of Vietnamese basa catfish farming.

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

Cole and Thuy aims to develop a product that would be administered by putting the vaccine-contained fingerlings in the water, and then place the fish in ponds for protection through harvest.

The strategy centres on making 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 project is aimed to help young scientists from Vietnam resolve problems on fish farmers and producers as aquaculture is a critical element of the country's globalisation programme and as well as to the welfare of Vietnamese households depending on aquaculture for living, according to Coloe.

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 metre, 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.