Researchers are urging closer monitoring of free-living amoebae—microscopic organisms found in soil and water—warning that some species can cause severe, sometimes fatal infections and can be difficult to control in water systems.
Free-living amoebae—single-celled organisms that occur naturally in soil and water—are drawing renewed attention as a potential public-health threat, according to a perspective published in the journal Biocontaminant.
While most amoebae are harmless, the authors note that some species can cause severe disease. One widely known example is Naegleria fowleri, often called the “brain-eating amoeba,” which can trigger a rare brain infection that is almost always fatal. U.S. health authorities say infection typically occurs when contaminated water enters the nose—often during swimming, diving, or other activities in warm freshwater—and the organism then travels to the brain.
The researchers argue that these amoebae can be unusually hard to control because some can tolerate conditions that would kill many other microbes, including high temperatures and high chlorine concentrations. Corresponding author Longfei Shu of Sun Yat-sen University said their survival traits can allow them to persist even in engineered environments such as water distribution systems.
Another concern highlighted in the paper is that amoebae can serve as protective hosts for other microbes. Bacteria and viruses can survive inside amoebae, where they may be shielded from disinfection—a dynamic often described as a “Trojan horse” effect. The authors say this could allow some pathogens to persist in drinking-water systems, and they cite research suggesting these environments may also contribute to the spread of antimicrobial-resistance genes.
The perspective links the risk to broader environmental pressures. Rising temperatures could expand the range and seasonality of heat-tolerant amoebae, increasing the likelihood of human exposure. U.S. public-health guidance notes that the geographic areas where Naegleria fowleri infections are confirmed have shifted over time, and that climate change may be a contributing factor.
To address the threat, the authors call for a “One Health” strategy that integrates public health, environmental science, and water management. They urge improved surveillance and detection, faster diagnostics, and more effective treatment technologies for water systems. “Amoebae are not just a medical issue or an environmental issue,” Shu said. “They sit at the intersection of both, and addressing them requires integrated solutions that protect public health at its source.”
The researchers also point to deteriorating water infrastructure and limited monitoring as factors that can increase risk, arguing that stronger oversight and updated safeguards will be needed as environmental conditions change.