Epidemiological Study of Pathogenic Leptospira in Raccoons (Procyon lotor) in a Suburb of Tokyo, Japan

Simple Summary Leptospirosis is a zoonotic infection, meaning that the pathological agent is transmitted between animals and humans. Raccoons are known to be one of the vectors, and there is an increasing concern regarding the spread of pathogens in Japan with expanding distribution and population of raccoons. We detected leptospiral DNA and antibodies in captured raccoons, and the prevalence and seroprevalence rates differed depending on the dispersal period of raccoons, showing that young males may spread Leptospira with dispersal. Furthermore, raccoons were found to contain Leptospira during warm and rainy seasons, which are suitable for the survival of Leptospira and wild rodents. Raccoons in urban environments may be more exposed to Leptospira. Leptospirosis is a zoonosis that affects humans and animals worldwide. Raccoons (Procyon lotor), adopted in urban environments, may act as potential reservoirs of Leptospira. We investigated the prevalence of pathogenic Leptospira in the kidney and urine samples of raccoons living in Tokyo, as well as anti-leptospiral antibodies in their serum, and aimed to examine the factors that expose raccoons to Leptospira. Polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA) were used to detect leptospiral DNA and anti-leptospiral antibodies, respectively. Thirty-six of 156 raccoons (23.1%) were positive by PCR, and 16 of 165 raccoons (9.7%) were positive by ELISA. The prevalence and seroprevalence rates differed depending on the raccoon dispersal period. We used univariable logistic regression to estimate the environmental factors associated with pathogenic Leptospira and anti-leptospiral antibodies in raccoons. Significant differences were observed in the PCR results for the seasons (spring-summer) (p = 0.01), average monthly temperature (p < 0.01), and average monthly rainfall (p < 0.01). No significant difference was seen in the ELISA results, but raccoons in larger urban areas tended to have higher seroprevalence rates (p = 0.06). We identified a pattern of leptospiral spread in raccoon dispersal and environmental factors that expose raccoons to Leptospira.

Automated summary

We detected leptospiral DNA and antibodies in captured raccoons, and found that the prevalence and seroprevalence rates differed depending on the dispersal period of raccoons, indicating that young males may spread Leptospira through dispersal. Additionally, raccoons were found to contain Leptospira during warm and rainy seasons, which are suitable for the survival of Leptospira and wild rodents. Raccoons in urban environments may have higher exposure to Leptospira.