A bacterial disease called “early mortality syndrome” has become a multibillion-dollar problem for the global shrimp-farming industry in the last year or so.
Shrimp are dying, production is down and prices are up.
That could soon change, thanks to a new diagnostic test developed by Linda Nunan, a University of Arizona assistant staff scientist, and Don Lightner, a UA professor of animal and comparative biomedical sciences.
The UA researchers, who identified the pathogen that caused the disease, have now developed a better, cheaper, faster way of testing for it, and have licensed the technique.
“Basically, the way you look for any new or old disease in shrimp is by testing diagnostically,” Nunan said, “and one of the fastest ways of doing that is by using polymerase chain reaction,” a widely practiced method for detecting diseases in different DNA sequences.
Lightner and Nunan’s diagnostic test targets the specific agent that causes early mortality syndrome, which kills shrimp right after they are stocked, Nunan said. It will allow shrimp farmers to quickly identify shrimp infected with the disease, she said.
Lightner and colleagues at the UA have developed several tests in the past for shrimp viruses, and promote the idea of “detect and slaughter” as a solution, rather than treating shrimp with antibiotics, he said.
Shrimp quickly become antibiotic-resistant, and the United States, Europe and Japan will reject imported shrimp if they have been treated with certain antibiotics, he said.
Lightner said he and Nunan recently teamed up with GeneReach Biotechnology in Taiwan to commercialize the test in kit form.
“We had hoped from the outset that (GeneReach) would get the technology,” he said. “We’ve been working with them for more than 10 years and have had a very good relationship with them.”
GeneReach “has a very good track record of developing kits for detection of shrimp pathogens, and they’re known worldwide,” Nunan said.
Once Nunan and Lightner have beta-tested the kits, they “will be marketed very fast because there’s a huge demand for it,” Nunan said.
She and Lightner expect the kits will be available by the end of this month.
One benefit of the test is that “because polymerase chain reaction has become pretty much the classic test for all shrimp viruses and bacterial diseases of note, labs around the world are set up to run this test,” she said.
Until now, the only way to detect early mortality syndrome was through the use of histology, which is how Lightner first described the disease in 2012, Nunan said.
She said histology is a lot more difficult because it involves looking at cellular changes within the tissue of a specimen. It also requires more processing equipment and takes longer to perform, she said.
The new test will be less expensive and produce results in 24 hours or less, she said.
Lightner and Nunan hope their work will help the global shrimp farming industry rebound.
The disease was mainly found in shrimp farms in Southeast Asia about a year ago, but has since spread to other places, including Sonora, Mexico, Lightner said.
Mexico “started to break with it in April or May, and had about an 80 percent loss,” he said. “When they restocked in July and tried again, it was even worse.”
Nunan said “it’s caused a lot of wipeouts in markets around the world — and it’s not just the shrimp farmers themselves, it’s also processing plants.”
Plants in Thailand “haven’t even been close to working at capacity from what we understand,” she said. “The disease does affect the livelihood of people.
“So we are hoping that the test will help mitigate the spread of the disease, for one thing,” Nunan said. “If used properly and for screening before you put your animals into the pond out of the hatchery, it should help.”
Lightner said they’re also hopeful that it will lower shrimp prices for consumers.
Last year, the U.S. imported about $6 billion in shrimp and consumed it more than any other seafood, Lightner said.