First overall report of Leptospira infections in wild boars in Poland.

Background: Recently an increase in the population of wild boars (Sus scrofa) in Europe has been observed. This is important from a zoonotic perspective because it influences directly on the spread of many diseases. For the first time, an extensive survey on the prevalence of Leptospira infections in Polish wild boars was performed. During the hunting season 2012-2014, 3621 blood samples from wild boars were collected. The animals originated from different geographical areas across Poland. Serum samples were tested by a microscopic agglutination test (MAT) for the presence of specific antibodies to the following Leptospira serovars: Icterohaemorrhagiae, Grippotyphosa, Sejroe, Tarassovi, Pomona, Canicola, Bratislava, Autumnalis, Hardjo and Ballum.

Results: Antibody titers to all Leptospira serovars except serovar Ballum were found in 377 serum samples (10.4 %). The highest number of seropositive wild boars was found in the south-eastern part of Poland and in highly urbanized areas such as Silesia and Łódź.

Conclusions: The relatively high prevalence of Leptospira infections in wild boars may constitute a threat to hunters and people having contact with forest lakes or marshlands. The results also indicate that an increasing population of wild boar living close to borders of cities may create additional risk for inhabitants in large urban areas.