Novel Leptospirosis Test Could Improve Treatment Options

Leptospirosis is a tropical disease that affects about 1 million people each year, causing nearly 60,000 fatalities worldwide. It spreads through contact with the urine of infected animals and can lead to severe illness, including jaundice, kidney injury, and pulmonary hemorrhage if not treated promptly. However, diagnosis has long been difficult due to the lack of sensitive and specific tests. A new diagnostic method now offers a promising way to identify the disease earlier.

Researchers at the Yale School of Medicine (YSM, New Haven, CT, USA) and Luna Bioscience (Groton, CT, USA) have developed a monoclonal antibody (mAb)-based capture immunoassay that targets virulence-modifying (VM) proteins. These proteins are a recently identified family of leptospiral exotoxins crucial to the disease’s pathogenesis. The new test detects these proteins in blood and urine samples, enabling the identification of infections much earlier than current methods.

Image: Hypothetical schematic representation of virulence-modifying (VM) proteins proteins in mediated leptospirosis pathogenesis (Chaurasia R. et al., Microbiology Spectrum (2025). doi.org/10.1128/spectrum.00018-25)

The team evaluated their approach using hamster models of leptospirosis. By detecting VM proteins circulating in the blood and urine, the assay successfully confirmed infection with high specificity. Their findings, published in Microbiology Spectrum, mark the first time leptospirosis has been identified as a systemic bacterial disease mediated by a toxin, comparable to tetanus or diphtheria, with potential for rapid antigen detection.

This breakthrough lays the foundation for developing inexpensive, easy-to-use diagnostics that could be deployed in resource-limited settings where the disease is most prevalent. Early detection would enable clinicians to begin treatment sooner, reducing fatalities and preventing complications. In addition to diagnosis, identifying VM proteins as central to the disease may also unlock new opportunities for therapeutic drug design and vaccine development.

“By enabling early detection, health care providers can initiate timely treatments, potentially saving lives and mitigating disease severity. Furthermore, understanding the role of VM proteins in disease pathogenesis could lead to new therapeutic targets and vaccine development opportunities,” said Dr. Joseph M. Vinetz, professor of medicine (infectious diseases) at Yale School of Medicine and senior author of the study.

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