Oregon and California are seeing an increase in the number of stranded sea lions along the coast due to leptospirosis, a bacteria that can also sicken dogs, livestock, people and other wildlife.

“Over the past few months, we have been getting calls for multiple sick or dead sea lions daily, which is higher than normal,” said Jim Rice, an OSU Marine Mammal Institute researcher who works at the OSU’s Hatfield Marine Science Center in Newport. At least eight cases of leptospirosis have been confirmed through OSU’s Oregon Veterinary Diagnostic Laboratory since the outbreak began in late September, mostly on beaches in Lincoln, Tillamook and Clatsop counties.

While leptospirosis occurs worldwide, outbreaks occur only sporadically in marine mammals, with the last Oregon outbreak seen in 2010. The disease can spread when an animal comes into contact with urine or other bodily fluids of an infected animal and can lead to kidney failure, fever, weakness, muscle pain, and other symptoms. In Oregon, young male sea lions are typically affected and usually show signs of dehydration, depression and reluctance to use their hind flippers.

While there is a small risk of transmission to people, dogs are most at risk of becoming infected by approaching stranded sea lions on the beach or coming in contact with body fluid from sick or dead sea lions. People walking their dogs on the beach should keep their dogs on a leash and not allow them to get close to stranded sea lions.

“Pets should be kept away from sea lions as leptospirosis can cause severe disease,” said Emilio DeBess, state public health veterinarian of the Oregon Health Authority. “Note that there are vaccines available to protect dogs and horses against leptospirosis, please contact your veterinarian for more information.

If your dog becomes ill after being exposed to sick or dead sea lions, contact your veterinarian immediately,” added DeBess.

People who observe sick sea lions or other marine mammals on the beach should say at least 50 feet away from them and report them to OSP at 1-800-452-7888. (OSP shares these reports with the Oregon Marine Mammal Stranding Network.)

Even when sea lions are healthy, it’s never a good idea to approach them. It’s also a violation of federal and state laws to harass, disturb, touch, or feed marine mammals.

For more information about leptospirosis, visit ODFW’s fact sheet or the Center for Disease Control website. For more information about wildlife diseases, contact ODFW’s wildlife health hotline at 1-866-968-2600.