November 10, 2006

US researchers one step closer to finding vaccine for coldwater disease
 

US researchers believe they may have found a way to immunize trout fingerlings from the coldwater disease, which kills vast numbers of trout in aquaculture ponds each year and cost fish farmers millions of dollars.

Ken Cain, associate professor of aquaculture and fish health at the University of Idaho and his team has worked on a vaccine for coldwater disease for the past six years.

Through experiments with thousands of trout fingerlings, the team discovered that trout were able to build up immunity to coldwater disease. The team is now trying to identify which proteins in the bacteria trigger the immune response.

Bacterial coldwater disease, caused by the gram-negative bacterium Flavobacterium psychrophilum transmitted both horizontally and vertically, with both male and female parents passing the pathogen on to their offspring.

Bacterial coldwater disease, caused by the gram-negative bacterium Flavobacterium psychrophilum, is a septicemic infection that originated in the North-western US and is responsible for significant losses of hatchery-reared salmonids worldwide.

Typical clinical signs of bacterial coldwater disease include lethargy, dorsal skin erosion, ascites (accumulation of fluid in the peritoneal cavity), bilateral exopthalmia, pale gills, and hemorrhagic vent with trailing mucoid casts. It often causes death if untreated.

The disease can cause a 30-45 percent loss rate in hatcheries.