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Leptospirosis - Kidney Damage in California Sea Lions

Every four to five years, The Marine Mammal Center sees a surge in the number of California sea lions that are admitted with symptoms of leptospirosis, a bacterial infection that affects the kidneys and can be lethal. If not treated, the bacteria can cause irreversible kidney damage.

Leptospirosis is caused by spiral-shaped bacteria called Leptospira. Veterinarians can usually identify leptospirosis in a patient even before laboratory tests confirm a diagnosis because of the infection's distinctive symptoms in California sea lions, which include drinking water and folding the flippers over the abdomen.

Marine mammals generally do not need to drink water because they receive all the hydration they need from food sources. But when they are infected with the Leptospira bacteria, their kidneys stop functioning properly and cannot filter toxins or regulate hydration.

If the disease is caught early enough, patients may recover with treatment that includes antibiotics, fluids and other supportive care, such as gastroprotectants for stomach and intestinal ulcers. But leptospirosis is often fatal because once the kidneys are damaged beyond repair, the animal will go into renal failure.

Outbreaks of leptospirosis in sea lions tend to occur in a cyclical pattern, and recent outbreaks have occurred in 2017, 2011 and 2008. In 2008, nearly 200 sea lion patients were admitted to The Marine Mammal Center with the infection. When a leptospirosis outbreak occurs, our scientists take advantage of the opportunity to study the disease and learn more about what causes an outbreak and how we can improve treatment for infected animals.

The graph above shows the seasonal nature of these outbreaks, reflected in large numbers of California sea lions stranding and being treated at the Center for clinical signs of kidney failure. © The Marine Mammal Center

With the Center’s 43 years of stranding records and bank of blood serum samples, we have been working with Dr. Katie Prager from the Lloyd-Smith Laboratory at UCLA to study the dynamics of this pathogen in the California sea lion population. The Center has been on the forefront of research on leptospirosis in marine mammals and has published a number of scientific papers on the disease dating back to 1985.

Since 2009, the Center's biologists and veterinary staff have taken blood and urine samples from wild juvenile California sea lions at popular haul-out spots in the San Francisco and Monterey Bay areas. These animals are then tagged and released, and the blood samples help researchers learn more about kidney function and exposure rates among these animals.

In California sea lions, leptospirosis outbreaks were first documented in the early 1970s. The reasons for repeated outbreaks in sea lions are unknown, as it is still unclear how this organism enters the marine environment. Recent studies suggest a combination of factors may be responsible, and more research is necessary to determine the causes of cyclical outbreaks in the population.

Many different animal species, including humans and dogs, can become infected with Leptospira bacteria through contact with contaminated urine, water or soil. The Marine Mammal Center has a number of safety protocols in place to prevent transmission to veterinarians and volunteers working with our sea lion patients.


How the Public Can Help:

  • Report sick marine mammals to The Marine Mammal Center by calling our 24-hour hotline at 415-289-SEAL(7325).
  • Maintain a safe distance of at least 50 feet and keep dogs away.
  • Support this life-saving work by making a gift today.


Leptospirosis Research at The Marine Mammal Center
Over the last 40 years, our veterinarians and scientists have contributed to a number of scientific papers on Leptospirosis, some of which can be viewed here:

Buhnerkempe, M.G., Prager, K.C., Strelioff, C.C., Greig, D.J., Laake, J.L., Melin, S.R., DeLong, R.L., Gulland, F.M.D., Lloyd-Smith, J.O. 2017. Detecting signals of chronic shedding to explain pathogen persistence: Leptospira interrogans in California sea lions. Journal of Animal Ecology. 86: 460-472.

Prager, K.C., Alt, D. P., Buhnerkempe, M.G., Greig, D.J., Galloway, R.L., Wu, Q., Gulland, F.M.D., Lloyd-Smith, J.O. 2015. Antibiotic efficacy in eliminating leptospiruria in California sea lions (Zalophus californianus) stranding with leptospirosis. Aquatic Mammals 41(2): 203-212.

Prager, K.C., Greig, D.J., Alt, D.P., Galloway, R.L., Hornsby, R.L., Palmer, L.J., Soper, J., Wu, Q., Zuerner, R.L., Gulland, F.M.D., Lloyd-Smith, J.O. 2013. Asymptomatic and chronic carriage of Leptospira interrogans serovar Pomona in California sea lions (Zalophus californianus). 164 (2013): 177-183.

Zuerner, R.L, Cameron, C.E., Raverty, S., Robinson, J., Colegrove, K.M., Norman, S.A., Lambourn, D., Jefferies, S., Alt, D.P. and Gulland, F. 2009. Geographical dissemination of Leptospiria interrogans serovar Pomona during seasonal migration of California sea lions. Veterinary Microbiology. 137: 105-110.

Cameron, C.E., Zuerner, R.L., Raverty, S., Colegrove, K.M., Norman, S.A., Lambourn, D.M., Jeffries, S.J., and Gulland, F.M. 2008. Detection of pathogenic Leptospira bacteria in pinniped populations via PCR and identification of a source of transmission for zoonotic leptospirosis in the marine environment. Journal of Clinical Microbiology, 46(5): 1728-1733.

Norman, S.A., DiGiacomo, R.F., Gulland, F.M.D., Meschke, J.S., and Lowry, M.S. 2008. Risk factors for an outbreak of leptospirosis in California sea lions (Zalophus californianus) in California, 2004. Journal of Wildlife Diseases, 44(4): 837-844.

Lloyd-Smith, J.O., Greig, D.J., Hietala, S., Ghneim, G.S., Palmer, L., St. Leger, J., Grenfell, B.T., and Gulland, F.M.D. 2007. Cyclical changes in seroprevalence of leptospirosis in California sea lions: endemic and epidemic disease in one host species? BioMed Central Infectious Disease 7: 125.


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