ABSTRACT

Background and Aim: Leptospirosis is an important zoonosis maintained through interactions among environmental reservoirs, wildlife, livestock, and humans. Despite ongoing veterinary surveillance, information on the environmental circulation of Leptospira spp. in Kazakhstan remains limited. This study aimed to investigate the circulation and diversity of Leptospira spp. in major aquatic ecosystems of Kazakhstan using metagenomic sequencing within a One Health framework, complemented by rodent surveillance and livestock serological data.

Materials and Methods: Surface water samples were collected during June–August 2021–2024 from 13 epizootiologically significant water bodies representing different climatic and hydrological zones of Kazakhstan. In total, 208 samples were examined using shotgun metagenomic sequencing to characterize the relative abundance and species composition of Leptospira spp. Rodent surveillance included serological testing and molecular examination, while livestock data comprised epidemiological records and serological monitoring of 8,617 animals from 17 regions. These complementary datasets were integrated to characterize environmental and animal-associated circulation of Leptospira spp.

Results: Leptospira spp. represented 0.4%–0.7% of bacterial sequences in surface water, with a mean relative abundance of 0.55% ± 0.15%. Among identified species, Leptospira interrogans accounted for 1%–39%, averaging 14.0% ± 13.0%, whereas Leptospira borgpetersenii and Leptospira kirschneri occurred at substantially lower proportions. Wild rodent seroprevalence during 2020–2025 was 0.09% (230/255,773), reaching 0.34% in great gerbils (Rhombomys opimus) in selected regions. Among reported livestock cases, cattle accounted for 50%, horses for 30%, and sheep and pigs for 10% each. Serological monitoring demonstrated regional seroprevalence of 1.1%–11.4% in cattle and 1.1%–6.6% in sheep.

Conclusion: The findings provide metagenomic and serological evidence of low-intensity Leptospira spp. circulation across aquatic ecosystems and animal reservoirs in Kazakhstan and demonstrate the value of integrated One Health surveillance. However, the absence of culture isolation and targeted molecular confirmation of environmental detections precludes confirmation of viable pathogenic leptospires. Prospective longitudinal surveillance integrating environmental, animal, and human sampling, physicochemical water characterization, culture isolation, and molecular confirmation is warranted.

Keywords: aquatic ecosystems, environmental metagenomics, Kazakhstan, leptospirosis, livestock, One Health, rodent reservoirs, zoonotic surveillance.