MSD Animal Health (known as Merck Animal Health in the USA and Canada) today introduced a new fish vaccine as a promising measure to help protect tilapia and other fish against the biotype 1 strain of Streptococcus agalactiae, which is the biotype specific to Thailand and other key tilapia-producing regions in Asia, including Malaysia.

“We are pleased to introduce a new fish vaccine to help producers protect their fish from one of the most costly diseases affecting the species,” said Norman Lim, Regional Technical Manager for aquaculture in Asia, MSD Animal Health. “The vaccine is backed by MSD Animal Health’s ‘Strep Control: Your Tilapia Health’ program, which provides producers with the support they need to implement an effective vaccination and control program.”

MSD Animal Health conducted extensive sampling of farms in the world’s most important tilapia-producing regions and found that Streptococcus accounted for 70 percent of all pathogens collected, making it the most prevalent disease affecting tilapia. Of the two Streptococcus strains that have been identified, S. agalactiae is the most economically damaging, causing widespread mortality and morbidity in larger fish.

In a laboratory test, fish experienced full onset of immunity one week after vaccination with this vaccine and protection was demonstrated to last for at least 12 weeks.1  In a large- scale field trial in an environment challenged by S. agalactiae biotype 1, the fish vaccine increased survival by 17 percent, increased biomass by 11.2 percent, and improved feed conversion efficiency by nine percent.  Protection was demonstrated for the entire grow-out period.

The fish vaccine provides specific protection against the biotype 1 strain of S. agalactiae, the main cause of Streptococcosis in tilapia in Thailand. Fish vaccinated with the vaccine are safe for human consumption.

As part of the ‘Strep Control: Your Tilapia Health’ program, MSD Animal Health can help producers confirm the strain and biotype present on their farm, implement a surveillance and vaccination program, and train staff on appropriate control strategies. Producers can consult their MSD Animal Health representative or a fish health professional to learn about MSD Animal Health’s ‘Strep Control: Your Tilapia Health’ program and the new fish vaccine.