Neglected leptospirosis in raccoons (Procyon lotor) in Indiana, USA.

Background: Leptospirosis is a globally important zoonotic disease occurring clinically and subclinically in humans and animals. Objectives: To determine whether raccoons in Indiana carried leptospires in their kidneys. Animals and methods: Thirty-four raccoons were live-trapped from two forest patches in central Indiana. Following euthanasia, a portion of kidney (2cm(2)) from each raccoon was homogenized and used for leptospiral culture. Leptospiral cultures were subjected to DNA extraction and various polymerase chain reaction (PCR) procedures reported previously. Serum sample from each raccoon was collected and antibody titers to leptospiral serovars were determined by microscopic agglutination test (MAT). Results: All leptospiral cultures were positive for Leptospira by various PCR procedures. The PCR with the primers targeting the conservative region of LipL32 gene was the most sensitive PCR in the detection of pathogenic leptospires. The variable LipL32 PCR amplicons were sequenced and compared to the reference strains available in GenBank. Twelve kidney cultures had Leptospira interrogans, eight had Leptospira kirschneri and two had Leptospira borgpetersenii. They were predominantly Grippotyphosa serogroup. Antileptospire antibodies were detected in 16 out of 34 raccoons (47.1%) by MAT. There were titers >= 1:80 in 16 raccoons (47.1%) and titers >= 1:400 in 3 raccoons (8.8%). The highest leptospiral serovar-specific seroreactivity among 34 raccoons was L. interrogans Bratislava (38.2%) and L. interrogans Grippotyphosa (32.4%). Conclusions: Raccoons in Indiana carry leptospiral organisms in kidneys and the leptospires are predominantly L. interrogans species and of the Grippotyphosa serogroup. Clinical importance: The raccoons serve as reservoir hosts that exposure sources to wildlife, livestock, pets and humans.