Molecular screening and characterization of Leptospira spp. in cattle and rodent populations in Morobe and East New Britain Provinces, Papua New Guinea

Leptospirosis is a globally important zoonotic disease with limited research documentation in Papua New Guinea. This study represents the first molecular-based investigation aimed at detecting and characterizing Leptospira spp. in cattle and rodent populations within Morobe and East New Britain Provinces. A total of 228 biological samples were collected from 9 different sites between January and March 2024, including 212 cattle samples (kidney, blood, and urine) and 16 rat kidney samples, followed by DNA extraction and conventional PCR amplification using secY and rrs (16 S rRNA) gene primers. PCR screening revealed that all 212 cattle samples tested negative for Leptospira spp., including samples from both vaccinated and non-vaccinated cattle farms. However, 2 out of 16 rat kidney samples (12.5%) from PNG UoT farm (Unitech) tested positive. DNA sequencing and phylogenetic analysis identified the positive isolates as Leptospira interrogans isolate P1D297, showing high genetic similarity to several uncultured Leptospira spp. isolates in the NCBI database, particularly isolates NRW30, NRW31, NRW54, NRW73, and NRW72. This study represents the second molecular confirmation of Leptospira diversity in rats in PNG and the first in Morobe Province, indicating potential transmission risks from rodent reservoirs to cattle populations and agricultural workers. These findings underscore the importance of integrated pest management strategies and enhanced surveillance protocols for effective leptospirosis control in agricultural settings.