A devastating leptospirosis outbreak is ripping through California sea lions. This ongoing crisis should be alarming not only to the public but to wildlife experts, conservationists, and health officials. This bacterial disease, infamous for putting the nation’s lettuce supply at risk of kidney failure, is on the rise, with more frequent outbreaks since 2018. Having been in the thick of that crisis, our experts say that the heightened awareness of the disease is critical because it can be fatal to humans, as well.
Similar to rabies, leptospirosis is transmitted primarily through bodily fluids, particularly urine. It has a near 100 percent mortality rate in California sea lions that are infected. Outbreaks have historically followed a three to five year pattern, but recent years show that the disease’s footprint is rapidly increasing. Recently, in 2018, the Marine Mammal Center received reports of over 300 sick sea lions. This staggering number really shows the crisis that we are in.
Understanding Leptospirosis
Leptospirosis is a zoonotic bacterial disease that is often asymptomatic in its animal hosts, but can cause serious disease in humans. In California sea lions it appears as renal failure, which poses overwhelming challenges for veterinary clinical care. The disease may require weeks or even months for recovery, making treatment of the disease difficult.
Giancarlo Rulli, a marine mammal veterinarian, remarked on the aggressive nature of the disease:
“Leptospirosis is an extremely virulent disease.”
This virulence is, unfortunately, reflected in the real world for many sea lions. These days, the Marine Mammal Center is confronting a hard truth. Approximately two-thirds of the animals that it rescues die in transit or due care, or require euthanasia following their admission evaluation.
The spread of Leptospirosis is not just a problem for California sea lions. It can impact many different species. This was the first demonstration of interspecies transmission, which has implications for effects on non-human wildlife and even domestic pets. Consequently, persistent and conscientious monitoring is needed to protect marine life and human health.
Historical Context and Environmental Factors
The incidence of Leptospirosis epizootics in California sea lions has been tightly associated with environmental factors. From late 2012 to 2017, a recurring phenomenon known as the “warm weather blob” developed. It shifted from the waters off Mexico up to the Gulf of Alaska. The unusually warm oceanic conditions may have disturbed foraging behavior and/or physiological health of the sea lions. This adverse environment provided fertile ground for diseases to flourish.
Experts are just starting to look at the increased frequency of outbreaks since 2018 as the alarming trend that it is. The Marine Mammal Center is on the frontlines, responding to outbreaks that are happening with increasing regularity. These outbreaks are turning out to be deadlier than last year’s.
As the epidemic situation faced by marine mammals such as California sea lions deteriorates, scientists urge people visiting beaches to be more informed. If you’re having some fun on the water or relaxing at the beach, be on the lookout! Contact local wildlife authorities as soon as possible when you spot sick or distressed sea lions.
Implications for Humans
Additionally, the link between Leptospirosis in sea lions and future threats to human health should not be discounted. Although the disease mainly affects animals, humans can become infected through exposure to contaminated water or soil. Symptoms in humans can include fever, chills, and muscle aches, so it’s important for ocean swimmers to take precautionary measures.
Awareness and education regarding Leptospirosis are crucial as it persists to affect and threaten our marine wildlife, as well as local human communities. Wildlife health officials recommend a broad range of people wash their hands thoroughly with soap after any contact with wildlife. They recommend avoiding beaches where sick sea lions may be located.