A hidden bacterial threat lurks in floodwaters and soil across the globe

Health · Published 29 September 2026 Swipe more like this →

In short: Leptospirosis is a global health challenge caused by Leptospira bacteria, often spread through the urine of infected animals. While many cases are mild, this disease can lead to severe organ failure and death. Understanding how it persists in our environment is critical for prevention, especially after heavy rainfall or flooding.

Leptospirosis, first described by Adolf Weil in 1886, is a zoonotic disease that affects both humans and a wide range of animals, including livestock, rodents, and pets. The bacteria are primarily transmitted through contact with urine from infected animals or through contaminated water and soil. Once these bacteria enter the body—typically through the eyes, nose, mouth, or skin abrasions—they travel through the bloodstream to the kidneys, where they can persist and be shed back into the environment.

The disease is a classic example of a One Health issue, requiring collaboration between human, animal, and environmental sectors. While common in tropical regions, it occurs worldwide, with an estimated 1 million cases and nearly 60,000 deaths annually. Environmental factors like flooding and poor sanitation significantly increase transmission risk, as floodwaters can spread contaminated urine into natural water sources. Research indicates that Leptospira can survive in moist soil and freshwater for weeks or even months, creating long-term exposure risks that extend beyond immediate contamination events.

Clinical presentation varies widely, from asymptomatic infection to the severe form known as Weil’s disease, characterized by jaundice, kidney failure, and bleeding. Severe pulmonary haemorrhage syndrome is particularly dangerous, with mortality rates ranging from 50% to 70% when the lungs are involved. Early treatment with antibiotics like doxycycline or penicillin is essential to prevent these complications. Because human vaccines are of limited utility, prevention relies on protective equipment, rodent control, and avoiding contact with potentially contaminated water, especially following extreme weather events.

General information, not professional advice. Spotted an error? Flag the card or see corrections and complaints.

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