Leptospirosis in northern elephant seals (Mirounga angustirostris) stranded along the California coast

Leptospirosis was identified in six northern elephant seals (Mirounga angustirostris) that were stranded in 1995 along the coast of California (USA). Histologic lesions in all seals included tubulointerstitial nephjitis with tubular degeneration and necrosis. Infection was confirmed through identification of spiro-chetes using an immunohistochemical stain for Leptospira sp. antigens. One affected seal had an elevated titer to Leptospira interrogans serovar pomna. Four of the six seals developed leptospirosis during rehabilitation, and two seals had evidence of exposure in the wild. Potential sources of infection during rehabilitation include other elephant seals, California sea lions (Zalophus califorianus), Pacific harbor seals (Phoca vitulina richardsh), or free-ranging wildlife. These results indicate that northern elephant seals are susceptible to leptospirosis and can develop disease both in the natural environment and in a rehabilitation setting.