Study of Circulation of Leptospirosis Pathogens in Different Regions of Vietnam

The territory of South-East Asia, including Vietnam, is one of the disadvantaged in relation to leptospirosis areas. According to studies, 10 % of the Vietnamese population is infected with Leptospira , but at the same time, information about circulating Leptospira species, the main carriers of infection in various regions of Vietnam, is very limited. The aim of the work was to investigate the circulation of leptospirosis pathogens in various provinces of Vietnam, for which a study of suspensions of small mammalian organs was conducted, and the level of the immune stratum of the population living in the surveyed territories was determined. Materials and methods . The work was carried out on the base of the mobile laboratory for monitoring and diagnostics, as well as the Laboratory of Toxicology and Tropical Diseases of the Institute of Tropical Medicine. Molecular-genetic methods (PCR and sequencing) were used to study 2,790 samples of suspensions of small mammalian organs collected in 14 provinces located in the northern, central and southern parts of the country between 2019 and 2024. Additionally, 576 sera from conditionally healthy people, obtained in 5 northern provinces of Vietnam, were studied by ELISA to assess the intensity of immunity to Leptospira . Markers of pathogenic Leptospira were detected in 282 samples from 20 different species of small mammals using PCR, while positive results were obtained in samples from all the provinces studied. 76 positive samples were sequenced, as a result of which appurtenance to the species Leptospira interrogans , Leptospira borgpetersenii , Leptospira mayottensis was established. Specific IgG class antibodies to Leptospira were detected in 8.0 % of the cases. A risk group has been identified – people employed in agriculture. The results obtained show the ubiquitous spread of leptospirosis pathogens in Vietnam. A promising field of research is the zoning of the country’s territories according to the intensity of epidemic manifestations of leptospirosis, the determination of the species composition of circulating Leptospira and the main carriers among mammals, taking into account the landscape, geographical and socio-economic factors.