With several hundred cases per year and several deaths, leptospirosis is a disease taken very seriously by the authorities. Researchers at the Institut Pasteur are working on the bacteria responsible for the disease.
Health authorities sounded the alarm bells last week. New Caledonia is experiencing a resurgence of leptospirosis cases. A total of 212 cases have been identified this year in the territory, once morest 50 to 150 per year usually. Two deaths are to be deplored in 2022, compared to five in 2020.
Lhe Institut Pasteur of New Caledonia has a dedicated unit research on this disease within it. Five people work there on the role of the environment in contamination.
Monthly cases of leptospirosis from January 1, 2021 to July 31, 2022 in New Caledonia
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Researchers at the Institut Pasteur have their eyes riveted through their microscopes on leptospira bacteria. For nearly six years, they have wondered regarding the role of the environment in the contamination of animals and humans. Research carried out on Grande Terre, and on their pilot site in Touho.
They have made it possible to demonstrate the risk associated with waterlogged soils, for example for people working in the fields.
“There is a really very large number and a very great diversity of leptospires in the soil and that somewhat supports our hypothesis that the real place of life of the leptospires is the soil.“explains Cyrille Goarant, Head of the Research and Expertise Unit on Leptospirosis at the IPNC. “In fact, that implies that there is also possible exposure when working the soil, therefore, when going to the fields or during agricultural activities. And then we were able to confirm by taking water samples from the Touho site that indeed, when the water in the creek is low and clear, there are very few or even no leptospires in the water and that as soon as we have a heavy rain and the water level rises and the water becomes dirty, at this time we have high concentrations“.
Incidence rate of leptospirosis by municipality in 2022
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Research is therefore continuing to try to understand the behavior of leptospires. How do these bacteria survive and persist in soils?
Roman Thibeaux, researcher at the Institut Pasteur, focused on the production of bacterial biofilm. A protective “armor” for leptospires, which allows them to survive. His environmental samples have shown that a single strain can persist for nine weeks in the environment.
” If we manage to modulate the production of biofilm, we can try to make the bacteria more sensitive to environmental stresses. This is why we are interested in this production of protective structures. What is interesting is that this biofilm is also produced in the kidneys of animals during chronic carriage. We think that this matrix, this biofilm that is produced in this context, also allows bacteria to be protected and to persist in the kidney of animals. There, it is perhaps something on which we might play, try to reduce the production of biofilm in the kidneys and suddenly to avoid chronic carriage and to have animals which are less infected by these bacteria“.
In total on the territory, 40 species of leptospira have been described by researchers.
