Warm-water-loving bacteria showing up in Alaska marine mammals

A type of stomach-turning bacteria that thrives in warm waters is starting to turn up in sea otters and other marine mammals that live off Alaska's Gulf Coast, an indicator of northern climate change, according to a newly published research paper authored by several Alaska veterinarians and biologists.

The bacteria is Vibrio parahaemolyticus -- Vp for short -- and it proliferates in waters at least 15 degrees Celsius (59 degrees F), is a fecal pathogen notorious for accumulating in shellfish and causing diarrhea, vomiting and other gastrointestinal woes in people who eat the shellfish.

That bacteria-related illness made its first documented Alaska appearance in 2004, when 62 cruise ship passengers were stricken with stomach pains and other ailments after eating raw oysters from Prince William Sound.

Until then, the northernmost outbreak of Vp-caused illness had been about 600 miles to the south, in British Columbia in 1997. The Alaska cruise ship outbreak was considered so significant that it was analyzed in the New England Journal of Medicine, which made the climate link.

The new report, published by the Alaska Sea Grant Program at the University of Alaska Fairbanks, describes the emergence of Vp in marine mammals since the 2004 oyster debacle.

From 2005 to 2013, 22 animals from the Gulf of Alaska, Cook Inlet, Prince William Sound and Bristol Bay were found to be carrying Vp. Almost all of the positive tests came from shellfish-gobbling sea otters. But two other animals -- a beluga whale and a porpoise -- also were found to be carrying the bacteria.

The findings came from routine tests performed on live and dead animals found stranded, live animals that were the subjects of biological studies and subsistence-harvested animals. Those tests were done by various organizations including:


• The Alaska SeaLife Center, which rescues and rehabilitates stranded marine mammals;

• The U.S. Fish and Wildlife Service, which operates animal-tagging programs;

• The National Oceanic and Atmospheric Administration; and

• State and private veterinarian offices.

Most of the animals found to be carrying the bacteria appeared to be unharmed, said Carrie Goertz, staff veterinarian at the SeaLife Center and one of the report's authors. A few particularly ill animals with Vp were suffering with a variety of ailments, but for them Vp was considered to be only a secondary problem, she said.

Discovery of animals with Vp "underscores the importance of these animals as sentinels for diseases circulating in the oceans" and shows that waters where the animals live have maintained temperatures warm enough to allow Vp "to proliferate to infectious levels," the report said.

Warming water is not the only factor sending Vp-related risks north, said Alaska state veterinarian Bob Gerlach.

That bacteria and other bacterial and viral pathogens are constantly changing to survive in new conditions, Gerlach said, including conditions created by a changing climate. "These bacteria are evolving and responding to stress, just like any other animal is, and they can adapt," he said.

There are new opportunities for invasive species -- including pathogens -- to be carried to Alaska, by human travelers, by ballast water and by other means, he said. And there are increasing interactions between domestic species, like oysters, and wild species, like sea otters, he said.

Several past studies have warned that climate change and various other factors make it more likely that numerous disease-causing pathogens will move north.

A 2005 study from the Centers for Disease Control's Arctic Investigations Program described likely increases in several types of infectious diseases. Increased ambient temperatures could result in more incidences of temperature-sensitive food-borne diseases like gastroenteritis, paralytic shellfish poisoning and botulism, said the study, authored by Drs. Alan Parkinson and Jay Butler. Increased flooding is expected to help spread water-borne diseases like giardia, the study said, while some animal population changes may bring about increased incidences of rabies.

One 2008 study -- co-authored by veterinarian Kathy Burek, who contributed to the new Vp paper – predicted that climate change would bring more disease and other health problems to Arctic marine mammals. A study published last year, co-authored by Gerlach, describes a predicted link between climate change and diseases passed between humans and animals, known as zoonotic diseases.

As for the diarrhea- and vomit-inducing strain of Vp now being carried by sea otters and other animals, state and federal officials have long been on alert.

The bacteria -- though no resulting illness -- appeared to have shown up in shrimp at a seafood plant in Petersburg in Southeast Alaska in 1973. That was, at the time, the northernmost documented appearance of the bacteria, according to the new Sea Grant report.

In 1995, the Alaska Department of Environmental Conservation began routine Vp screening of oysters. The positive test nine years later came during a particularly warm summer, but there are indications that warm conditions will persist in the future, the scientific paper said.

"The 2004 outbreak was a wake-up call to folks that it is possible to get this disease in Alaska," Goertz said.

Since 2004, almost all of the Vp-related illnesses contracted by Alaskans have involved people who ate fish from outside the state, some of whom got sick after coming home from their travels, said George Scanlan, shellfish permit coordinator for DEC.


The exception occurred last year in Ketchikan, when a woman fell ill after eating oysters at a local restaurant, Scanlan said. The DEC investigation revealed that the oysters in her meal came from a local southeast Alaska farm, he said.

Health and environmental officials have tips for avoiding Vp-related illness from oysters and other shellfish: Rinse the fish thoroughly in cold water, keep the fish chilled and cook it before eating.

Contact Yereth Rosen at yereth(at)

Yereth Rosen

Yereth Rosen was a reporter for Alaska Dispatch News.