Development and Validation of a Polymerase Chain Reaction (PCR) Assay to Detect Leptospiruria in California Sea Lions (Zalophus californianus)
Center for Companion Animal Health, School of Veterinary Medicine, University of California, Davis, CA, USA
Leptospirosis is a disease of humans, wildlife, and domestic animals found worldwide, and caused by spirochete bacteria of the genus Leptospira. A definitive diagnosis of leptospirosis requires the agent be cultured from the host; unfortunately, culturing of Leptospira usually requires at least 2 months, is very laborious, and results in a low isolation rate from infected subjects. Polymerase chain reaction is an alternative method of diagnosing leptospirosis. Urine samples, obtained from four control dogs, were seeded with five different serovars of pathogenic Leptospira at six different dilutions. The overall sensitivities across the five serovars ranged from 0.935 to 0.964. Twenty-five urine, kidney, and serum (23) samples were obtained from California sea lions that presented at the Marine Mammal Center (Marin, CA) in the autumn of 1999. Of these 25 animals, 24 were found to be positive for leptospirosis based on a combination of serology, PCR, sequencing, and histopathology. The sensitivity of PCR with subsequent DNA sequencing was 0.875. This sensitivity demonstrates that PCR will be a useful tool in the diagnosis as well as the description of the epidemiology of leptospirosis.