The Norway rat (Rattus norvegicus) is the main reservoir of one of the most disease inducing species of Leptospira, L. icterohaemorrhagiae. In Denmark there are only a few yearly registered cases of L. icterohaemorrhagiae derived leptospirosis in man, but in general the disease is believed to much more abundant. Previous research programs have focused on monitoring Leptospira sp. in rural rats and dates back to the 1980ties. To determine the prevalence of leptospires in sewer rats, we therefore initiated a study ultimo 2006. Up to 80 % of rat incidences in urban areas may be related to sewer rats and knowledge of leptospires in these populations may thus reflect the prevalence of infection in urban surface populations. Approx. 30 rats were captured from six different locations in the suburban area of Copenhagen. All rats were screened for a total of six pathogenic leptospires: L. noguchii, L. santarosai, L. meyeri, L. interrogans, L. weilii and L. borgpetersenii by PCR. PCR was performed on DNA extracted from kidneys with primer G1/G2 which amplifies a leptospira DNA fragment of 285 bp. For determination of leptospira serovar types, PCR was combined with MAT (Microscopic Agglutination Test). Preliminary results based on one fourth of the captured rats indicate, that the prevalence of pathogenic leptospira infected sewer rats are relatively high, as 28 out 48 rats were positive by PCR. This suggests that the sewer could be an environment representing high prevalence of leptospira among rats and thus an environment with high risk of transmission.
Leptospira; L. icterohaemorrhagiae; Rattus norvegicus; Sewer rats; PCR
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European Vertebrate Pest Management Conference, 2008