A deadly herpes virus is threatening oysters world-wide

Oysters, a delicacy eaten on most coastlines of the world, are a multi-billion-dollar industry. They also are intriguing to study from a health perspective. Oysters feed by filtering tiny plankton from the surrounding water, processing up to 50 gallons per oyster daily. In doing so, they improve water quality and make their ecosystems healthier. But the water that they grow can be filled with disease-causing microorganisms that can affect both oysters and humans.

Today a deadly herpes virus, Ostreid herpesvirus 1 (OsHV-1), is threatening Pacific oysters (Crassostrea gigas), the world’s most popular and valuable oyster species. It is almost certain to spread more widely in our globally connected world.

I know what you’re thinking: “Oysters get herpes??” Yes, and they can also can get sick from other types of pathogens and stresses. But you won’t contract this virus from eating an oyster, whether you enjoy them on the half-shell or cooked. OsHV-1 can infect other bivalve species, like some animal herpes viruses that can cross species barriers, but it is genetically distinct from other animal herpes viruses and does not infect humans.

With support from the NOAA Sea Grant aquaculture program, I’m working with a diverse team that includes researchers, regulators and outreach specialists in the United States and abroad to better prepare the U.S. oyster industry for the spread of this virus.

Dead Pacific oyster sampled during a OsHV-1 mortality event this summer in Tomales Bay, California. Colleen Burge, CC BY-ND

Deadly and spreading

Pacific oysters are native to Asia and are the most popular and valued oyster for aquaculture globally. Humans transferred them from their native range to multiple grow-out areas globally, including France, the United States and Australia. They are the primary species grown on the U.S. West Coast, whereas both wild and cultured Eastern oysters grow on the East and Gulf coasts. In contrast to Eastern oysters, Pacific oysters were relatively resistant to infectious diseases until OsHV-1 emerged in the early 1990s.