Aim: This study aimed to find out the prevalence of active infection of Leptospira spp. in Rattus norvegicus from Grenada, West Indies, through polymerase chain reaction (PCR).

Materials and Methods: One hundred and forty-nine rats were trapped, anesthetized and their kidneys collected aseptically. DNA was extracted from the kidney tissue of each rat. PCR was performed targeting LipL32 gene. Eighteen PCR-positive amplicons for LipL32 gene segment were purified and sent for direct sequencing to the sequencing facility of MCLAB (South San Francisco, USA). Results of sequencing were read and interpreted. The prevalence of Leptospira spp. in relation to sex and age was also recorded.

Results: All amplified sequences were compared to the sequences present in GenBank using basic local alignment search tool (BLAST) from the online website National Center for Biotechnology Information, the results revealed that six samples had similarity to Leptospira interrogans strain 1399/2016 and eight samples had similarity with Leptospira borgpetersenii serovar Hardjo-bovis strain L49. Of 149 kidney samples, only 14 were positive for Leptospira spp. by PCR giving an incidence of 9.3%. There was no significant difference found in relation to sex and age.

Conclusion: This is the first report confirming active infection of Leptospira spp. in Rattus norvegicus in Grenada using PCR. The presence of active infection in rats can be considered as high risk for humans. Further research to understand the epidemiology of leptospirosis in Grenada is suggested.

Keywords: Rattus norvegicus, Grenada, kidney, Leptospira spp., polymerase chain reaction.