Between May 1984 and February 1985 approximately 226 California sea lions (CSLs) with leptospirosis were noted, diagnosed and treated by members of the California Marine Mammal Center and the University of California, Berkeley, Department of Biomedical and Environmental Health Sciences. The animals, primarily 2 to 3 year old males, exhibited severe depression, excessive aggression, polydyspsia, and a "hunched-up" appearance. Renal failure was characterized by high BUN, creatinine and phosphorous values; positive diagnosis was made serologically and via dark-field microscopy of urine and renal tubules Wharton silver stain.

Antibiotic therapy included tetracyclines (10 mg/# tid p.o. for 7-10 days) or penicillin (Dual-Pen® 10,-20,000 u/# sid lM) in anorexic animals. Severely affected animals were stomach-tubed water and fish wash to assist with rehydration.

The epidemiology of the outbreak will be explored as well.