Marine Mammal Bites Information for Local Health Departments
Background
California's coastal beaches draw millions of visitors every year. Beachgoers can occasionally encounter large marine mammals (most notably sea lions, seals, and sea otters) while swimming, surfing, or engaging in other recreational activities. Reports of bite and scratch wounds following these interactions are infrequent but do happen. Acute or chronic exposure to environmental toxins (domoic acid from algal blooms) in sea water can cause encephalitis in marine mammals and precipitate abnormally aggressive behaviors leading to human injury.
Zoönotic Pathogens of Concern
Health care providers may consult with local health departments on management of patients who sustain injuries from a marine mammal encounter. In addition to tissue trauma, marine mammal bites can facilitate the transmission of infectious disease agents.
Rabies
Although all mammals are susceptible to rabies, the virus has not been isolated from marine mammals in California. Therefore, bites from seals, sea lions, and sea otters pose a negligible risk for rabies transmission to humans.
Tetanus
Clostridium tetani has not been isolated from marine mammals but has been detected in marine sediment, making tetanus a concern for any penetrating wound.
Localized Infection
Any bite wound can serve as a source for localized infection. There are limited, published studies on the microbiology of marine mammal bite wounds. Mycoplasma phocacerebrale and Bisgaardia hudsonensis (member of Pasteurellaceae family) are commonly isolated from seal and sea lion bites and have previously guided choice of prophylactic antimicrobials. But given the variety of aerobic and anaerobic bacteria present in the animal's oral cavity and in sea water, antimicrobial treatment should ideally be based on culture and sensitivity results from an evident infection.