Severe Sea Lion Bites in Urban Cold-Water Swimmers

A series of sea lion bites in open-water swimmers recently gained the attention of the national and international media. Pinniped (the clade including seals and sea lions) bites historically have been in people who hunt or handle marine mammals. As populations of humans and pinnipeds continue to grow, interactions with animals by those participating in recreational activities are likely to become more frequent.

In December of 2017 and January of 2018, four sea lion (Zalophus californianus) bites in humans occurred at a popular open-water recreational swimming area in San Francisco, California. Three swimmers required treatment at a local trauma center and two required surgery. Two of the wounds were potentially life threatening; one swimmer required a field tourniquet to stop bleeding from the antecubital fossa, and the bite in another narrowly missed the femoral artery. The purpose of this report is to offer an in-depth discussion of antimicrobial use and rabies postexposure prophylaxis in patients with severe pinniped bites. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Information from this report can be used in conjunction with input from local experts to develop a thoughtful therapeutic plan for patients with severe pinniped bites. Doxycycline is the first-line antibiotic therapy, but broader coverage may be needed for severe wounds with the potential for contamination. The likelihood of rabies is low, and rabies postexposure prophylaxis should be reserved for cases that involve unusually aggressive animal behavior or other factors suggestive of rabies.