The development of an effective vaccine is Chile’s best (only?) hope to prevent a persistent bacterial disease from potentially causing further damages to its farmed salmon and trout industries. It could also sooth the sting for Chile, which is now known as the world’s largest consumer, by a wide margin, of aquaculture antibiotics.
Last week, Oceana took Chile to task for its heavy dependence on antibiotics. The reported 993,000-pound total that Chile used in 2013 is staggering when compared to other countries with large-scale salmonid farming operations. Chile, the No. 2 Atlantic salmon producer in the world, used 472 times as many antibiotics by volume as No. 1 producer Norway.
For the SeaFood Business Top Story in March, I reported that Chile had used 337,990 kilograms (744,929 pounds) of antibiotics in 2012. At first look, the figure appeared to be an error. But it wasn’t. And then antibiotic use increased 33 percent again last year.
It could have been even higher, as some 50 Chilean salmon companies refused to disclose their antibiotic consumption to Oceana because it would “threaten their business competitiveness.” With or without that data, it’s clear that antibiotic use has become the industry’s crutch and, currently, its best weapon against the formidable pathogen Piscirickettsia salmonis, which causes Salmon Rickettsial Syndrome (SRS). The bacterial disease leads to internal hemorrhaging and necrosis in the kidneys and other organs.
The disease has been plaguing the industry for 25 years or more and is one of the top concerns for salmon and trout producers in that region of the world right now. Peter Bridson, aquaculture research manager for the Monterey Bay Aquarium, says the challenge is “huge” and the only alternative solution is a vaccine. It’s particularly important as the U.S. Food and Drug Administration considers the antibiotics that Chile is employing to be “highly important” to human health (not, as should be noted, in the “critically important” category).
“There are a few vaccines are in the pipeline,” said Bridson and if an effective one is developed, he added, Chile can drastically reduce the mortality rates seen in SRS-affected areas. “Chile has not managed that yet. It’s interesting that it’s one disease that keeps coming up. It’s an environmental pathogen that’s getting them time and time again.”
Keep in mind that Chile is also still recovering from a devastating outbreak of infectious salmon anemia (ISA), caused by a virus that antibiotics, in theory, would have little to no impact on. According to multiple sources, antibiotics were used extensively in the ISA crisis as well.
Drug manufacturer Advanced BioNutrition (ABN) of Columbia, Md., U.S., developed an oral SRS vaccination for salmon and trout. ABN last year reported promising results from a vaccine it licensed to Centrovet Laboratories in Chile. Antimicrobial agents have thus far proven ineffective.
Can Chile kick its drug habit? Bridson believes so, adding that trials up to this point have not proven to be fully effective, or the immunization process is effective for one part of the fish’s life cycle but not another.
“Most of the other countries that had higher level dropped dramatically because of vaccines,” he said. “You would hope there’s a solution in the near future.”
With heightened concerns regarding antibiotic use in food animals and the potential for humans to build up a resistance to these important drugs, the impetus for vaccination is clear.
