Prevalence of Antibody to Six Leptospira Servovars in Swedish Wild Boars

Zoonotic Leptospira bacteria are pathogens that may increase in importance with climate change. We investigated the prevalence of antibody to six Leptospira serovars (sv) in the Swedish wild boar (Sus scrofa) population, which is increasing in number and geographic distribution. The serovars we selected cause disease in pigs or may be of use as sentinel serovars to measure the potential spread in Swedish fauna. In total, 386 serum samples from wild boars collected between 2005 and 2007 were investigated using a microscopic agglutination test for Leptospira interrogans sv Bratislava strain Jez Bratislava, sv Icterohaemorrhagiae strain Kantorowicz, sv Pomona strain Pomona, Leptospira kirschneri sv Grippotyphosa strain Duyster, and Leptospira borgpetersenii sv Tarassovi strain Perepelitsin, and a domestic strain closely related to sv Sejroe. Twelve (3.1%) of the analyzed samples were antibody-positive. Of those, nine (2.3%) were positive for sv Bratislava and 0.8% for sv Icterohaemorrhagiae. All antibody-positive samples originated from areas where wild boars are reported to be common. We conclude that Leptospira infection is less common in Swedish wild boar than in continental Europe. However, we recommend continuous surveillance to follow the effects of climate change and an increasing wild boar population.