SLO County sea lions hit with potentially deadly infection

A highly contagious and potentially fatal bacterial infection is sweeping California’s sea lion population — and 16 San Luis Obispo County animals have been affected in what The Marine Mammal Center says is the second-largest outbreak recorded along its response range.

Since January 1, the center has confirmed 220 cases of leptospirosis along its 600-mile response range from SLO County to Mendocino County and says an active outbreak is occurring.

The last recorded leptospirosis outbreak, in 2017, affected just a handful of sea lions in SLO County, according to Giancarlo Rulli, spokesman for the Marine Mammal Center. Rulli added that SLO County doesn’t typically see as many leptospirosis cases as other areas in the center’s response range, though the area does see more cases of domoic acid poisoning.

The center said it sees a surge in the number of sea lions admitted with symptoms of leptospirosis every four to five years. Before the 2017 outbreak, the most recent ones occurred in 2011 and 2008. During the 2011 outbreak, about 200 sea lions infected with leptospirosis were admitted to the center, according to a news release.

E. CSL_Ziggy_Leptospirosis tucking position_© The Marine Mammal Center_preview
A California sea lion at The Marine Mammal Center in Sausalito displays signs of abdominal discomfort due to leptospirosis. The Marine Mammal Center

Since most leptospirosis cases occur between July and November, the center is preparing for “a continued spike in sea lion patients this year,” according to the release.

If leptospirosis is not caught and treated in time, the infection can result in kidney damage and renal failure.

Symptoms of the infection in sea lions include drinking water and folding their flippers over their abdomen. Generally, sea lions don’t need to drink water because they receive all the moisture they need from food, the Marine Mammal Center said. When they’re infected with leptospira bacteria, their kidneys stop functioning properly and can’t filter out toxins or regulate hydration.

Because leptospirosis is spread through urine, dogs and humans are also at risk for the infection through contact with contaminated urine, water or soil, according to the Marine Mammal Center.

To report a sea lion that may be infected with leptospirosis, call the Marine Mammal Center’s 24-hour hotline at 415-289-7325. The center also reminds the public to stay at least 50 feet away and to keep dogs away as well.

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