Virus Responsible For Sea Star Wasting Disease Discovered

Chuck Bednar for redOrbit.com – Your Universe Online
Over the past 18 months, experts have been puzzled by the unusual and gruesome deaths of millions of starfish along the Pacific Coast of North America, but now the authors of a new Proceedings of the National Academy of Sciences study have discovered the pathogen responsible for the phenomenon.
Ian Hewson, a professor of microbiology in the Cornell University College of Agriculture and Life Sciences, and his colleagues have identified the mysterious disease that causes the limbs of the sea stars to pull away from their bodies and their organs to exude through their skins as Star Associated Densovirus (SSaDV).
[ Watch the Video: Researchers Examine Sea Star Associated Densovirus ]
SSaDV is a type of parvovirus commonly found in invertebrates, and according to Jane J. Lee of National Geographic, it is a type of parvovirus similar to the pathogen that cause gastrointestinal problems in unvaccinated dogs. The bad news is that, even though the researchers now know the cause, there’s little they can do to stop the virus.
“We can’t quarantine, we can’t effectively cull, and we can’t vaccinate,” co-author Drew Harvell, a marine ecologist at Cornell, told Lee during an interview earlier this year. However, in a statement released Monday, Harvell said that the research does lay the groundwork for learning more about how the densovirus kills sea stars and what exactly causes outbreaks of the disease known as Sea Star Wasting Disease (SSWD).
“It’s the experiment of the century for marine ecologists,” Harvell said, explaining that the ocean floor-dwelling sea stars are voracious predators and play a vital role in maintaining the biodiversity of their ecosystem. “It is happening at such a large scale to the most important predators of the tidal and sub-tidal zones. Their disappearance is an experiment in ecological upheaval the likes of which we’ve never seen.”
According to the Natural History Museum of Los Angeles County, which provided specimens for the researchers to analyze, the study indicates the virus has survived at a low level for more than seven decades. It was detected in preserved sea stars that were collected as early as 1942 and as recently as 1991, and the study suggests that SSaDV may have recently risen to epidemic levels due to starfish overpopulation, environmental changes, or mutation of the virus.
While Lee said that the long-term impact of the virus remains to be seen, currently infected sea stars such as the sunflower star and the purple or ochre star wind up meeting a gruesome end. SSaDV weakens the creature, leaving it vulnerable to bacterial infection that ultimately kills the starfish, Hewson explained. Within eight to 17 days after becoming infected, their bodies become covered in white lesions and they become lethargic. Sometimes, their arms rip themselves off and walk away, Lee said, and ultimately it winds up deflating into a pile of white slime.
“The recent outbreak of sea star wasting disease on the U.S. West Coast has been a concern for coastal residents and marine ecologists,” said David Garrison, program director at the National Science Foundation (NSF) Division of Ocean Sciences. “This study… has made a significant contribution to understanding the disease.”
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