Leptospirosis is the most common zoonotic infection in the world which can affect both animals and humans. This infection is endemic in tropical regions, although its incidence also increases in temperate regions.
In detecting antibodies against the bacteria, a standard serological diagnostic test, called Microscopic Agglutination Test (MAT) uses live Leptospira strains. To enhance its specificity and sensitivity, it is recommended to use locally circulating strains. However, no local strain is available in other countries such as Austria.
Search for Pathogenic Strain
To close this research gap, a study was conducted to isolate circulating Leptospira strain from Austrian cattle. The details of the experiment are described in the paper "First isolation and genotyping of pathogenic Leptospira spp. from Austria."
Led by Cynthia Sohm, the research team identified a variant in Austria called Leptospira borgpetersenii serogroup Sejroe serovar Hardjobovis. Genetic analysis revealed that it is extremely adaptable and can be found in both domestic and wild ruminants.
The team also discovered that cattle on Austrian farms can carry the bacteria and can be a source of infection for humans and other animals. According to epidemiologist Amélie Desvars-Larrive, the strain has potential zoonotic risk, especially in settings characterized by close interaction between humans and animals.
Desvars-Larrive also noted that the identified strain is already widespread in parts of Europe and North America. It has also been found in wild and farm animals and in humans.
Until now, Austria has used Leptospira variants from abroad in diagnosing the disease in humans and animals. By achieving the first isolation and genotyping of this pathogen, it will now be possible for the national laboratory to use this strain. In short, the test performance can be improved due to the availability of the local strain.
Bacteria Characterization Process
Scientists in Austria faced a lot of challenges in their search for the infectious pathogen. In 2021 and 2022, Desvars-Larrive and her colleagues from the Complexity Science Hub, Austrian Agency for Health and Food Safety (AGES), and Vetmeduni performed targeted sampling to maximize the chance of isolating Leptospira in a non-endemic country. They search for infected animals by using statistical methods, literature review, and a farm network.
The research team was able to take samples from 410 cattle. Five of them tested positive for leptospirosis. The team also successfully isolated, cultivated, and precisely identified the bacteria three times.
Various challenges were faced by the team during the characterization process due to the fact that Leptospira cultivation is very time consuming. Pathogen samples had to be in the laboratory within two to six hours. The bacteria also need a complex medium where antibiotics protect them from being contaminated by other bacterial strains.
The samples also need to be cultivated for between 7 and 23 weeks before they can be observed. Finally, the pathogen was isolated from cultures and was genotyped at the Institut Pasteur in Paris. Certain components of the genetic material were sequenced to allow precise characterization of the bacterial strain.
Desvars-Larrive believes that their study can help raise awareness of the dangers of leptospirosis. Although Austria has so far considered the disease relatively harmless, the risk of infection may increase in Europe in the future due to global warming and related flooding events.
Check out more news and information on Bacteria in Science Times.
