title: Geographical dissemination of Leptospira interrogans serovar Pomona during seasonal migration of California sea lions.
abstract: Leptospirosis is one of the most widespread bacterial zoonoses in the world and affects most mammalian species. Although leptospirosis is well documented and characterized in terrestrial species, less information is available regarding the distribution and impact of leptospirosis in marine mammals. Additionally, the role of animal migrations on the geographical spread of leptospirosis has not been reported. Periodic epizootic outbreaks of acute leptospirosis among California sea lions (Zalophus californianus) have been reported since 1971. In this study, we collected samples from California sea lions stranded along the Pacific coast of North America during the most recent epidemic in 2004, and maintained leptospirosis surveillance of the California sea lion population along the California coast through 2007. Several isolates of Leptospira interrogans serovar Pomona were obtained from kidney and urine samples collected during this study, a finding consistent with serological evidence that California sea lions are persistently exposed to this leptospiral serovar. Combined, these data support a model whereby California sea lions are maintenance hosts for L. interrogans serovar Pomona, yet periodically undergo outbreaks of acute infection. During the 2004 outbreak, the incidence of new leptospirosis cases among California sea lions coincided with the seasonal movement of male sea lions from rookeries along the coast of central and southern California north as far as British Columbia. These data show that seasonal animal movement contributes to the distribution of leptospirosis across a large geographical region.
authors.affiliation: Bacterial Diseases of Livestock, National Animal Disease Center, P.O. Box 70, Ames, IA 50010, USA. Richard.Zuerner@ars.usda.gov
authors.forename: Richard L
authors.initials: RL
authors.lastname: Zuerner
authors.forename: Caroline E
authors.initials: CE
authors.lastname: Cameron
authors.forename: Stephen
authors.initials: S
authors.lastname: Raverty
authors.forename: John
authors.initials: J
authors.lastname: Robinson
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Colegrove
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: Norman
authors.forename: Dyanna
authors.initials: D
authors.lastname: Lambourn
authors.forename: Steven
authors.initials: S
authors.lastname: Jeffries
authors.forename: David P
authors.initials: DP
authors.lastname: Alt
authors.forename: Frances
authors.initials: F
authors.lastname: Gulland
mesh_terms: D025041:Animal Migration; D000818:Animals; D001955:British Columbia / Q000453:epidemiology; D004196:Disease Outbreaks / Q000662:veterinary; D041401:Leptospira interrogans serovar pomona / Q000302:isolation & purification*; D007922:Leptospirosis / Q000453:epidemiology / Q000662:veterinary*; D019601:Pacific States / Q000453:epidemiology; D046070:Sea Lions; D012621:Seasons