Scientists are urging immediate global action as so-called free-living amoebae spread into new regions, driven by climate change and failing water infrastructure, according to new research summarized by ScienceDaily. These microscopic organisms, long present in soil and freshwater, are increasingly being recognized as an emerging public health threat with the potential to cause severe and often fatal infections.
Free-living amoebae are single-celled organisms that thrive naturally in the environment. While most species are harmless, a small number can infect humans under specific conditions. The most notorious example is Naegleria fowleri, commonly known as the brain-eating amoeba, which can cause a rare but almost always deadly brain infection when contaminated water enters the nose during swimming or other water activities.
Researchers say these organisms are especially dangerous because of their extreme resilience. They can survive high temperatures, tolerate strong disinfectants such as chlorine, and persist inside water distribution systems that are generally considered safe. According to the study’s corresponding author, Longfei Shu of Sun Yat-sen University, this makes them far harder to control than most waterborne microbes. The research has been published here.
The threat extends beyond the amoebae themselves. Scientists warn that these organisms can act as protective hosts for other pathogens, including bacteria and viruses. By living inside amoebae, these microbes can evade standard water treatment processes, a phenomenon often described as a “Trojan horse” effect. This hidden survival mechanism may also contribute to the spread of antibiotic resistance by allowing bacteria to persist in hostile environments.
Climate change is expected to accelerate the problem. Rising global temperatures create favorable conditions for heat-tolerant amoebae, enabling them to expand into regions where they were previously rare. In parallel, aging water systems and limited monitoring mean many infections may go undetected until serious illness occurs. Several recent cases linked to recreational water exposure have already heightened concern among public health officials.
The researchers are calling for a coordinated One Health response that integrates public health, environmental science, and water management. They argue that improved surveillance, faster diagnostic tools, and more advanced water treatment technologies are urgently needed to reduce risk before infections occur. As the authors note, amoebae sit at the intersection of environmental change and human health, making early intervention critical to preventing a wider global threat.