Investigating rodents and environmental samples as possible sources of Leptospira infections in the Mnisi communal area, Bushbuckridge, South Africa

Abstract

Leptospirosis is an important bacterial infection of both animals and humans, largely neglected worldwide. Leptospirosis occurs worldwide and is maintained in numerous animal hosts. The aim of this study was to investigate rodents as a potential source of pathogenic Leptospira spp. infection within the Mnisi community where a previous outbreak of human leptospirosis had occurred in 2018. The Mnisi community is a rural community, situated at the wildlife-livestock-human interface within the Bushbuckridge Local Municipality, Mpumalanga Province of South Africa. As part of the study, soil and water samples were also tested for the presence of pathogenic Leptospira spp. bacteria to investigate the potential of environmental sources negatively affecting human health. Our research included three aspects: biobank samples collected from Athol, Gottenburg, Utha and Thlavakisa villages from September 2020 until March 2022; rats trapped from Welverdiend A in April 2022 and environmental samples collected from all five villages in April 2022. For trapping in Welverdiend A, eight traps were set per household, with a total of 25 households. These traps were set in the late afternoon, baited with peanut butter and oats, left overnight and checked in the early mornings, for a total of four trapping nights. The traps were placed in strategic areas around the household where they were safe from predators. After collection, the rats were euthanized and kidneys dissected for further processing. DNA was extracted making use of the Invitrogen PureLink Genomic mini kit, where-after a real-time PCR specific for pathogenic Leptospira was performed. Environmental samples included both soil (25 samples) and water (25 samples) collected from strategic areas throughout the five villages. DNA was extracted using the Zymo Quick-DNA Fecal/Soil Microbe MiniPrep Kit and a real-time PCR was performed. GPS coordinates and photographs were taken of all environmental sample collection sites. A total of 158 rodent kidney samples was analyzed, comprising 124 biobank samples (from Athol, Utha, Gottenburg and Thlavakisa) and 34 fresh samples collected from Welverdiend A. None of the rodent kidney samples contained enough pathogenic Leptospira spp. bacteria for DNA to be detected. Twenty-five soil and 25 water samples were processed from all five villages (five of each from each village) and no pathogenic Leptospira spp. were detected. This project was the first of its kind for the study of leptospirosis in the Mnisi community and forms part of the very limited information that is available on leptospirosis within South Africa. Although all samples returned a negative result, this study is still valuable as any information on the prevalence of Leptospira spp. and its potential reservoir hosts is important to guide further studies. The sample population was quite small due to limited funding and more in-depth research on pathognenic Leptospira spp. within the Mnisi Community, Bushbuckridge, would prove to be exceptionally valuable.