A collective of environmental and public health researchers has raised serious concerns over free-living amoebas, warning that these organisms could become an increasing global health risk. Their concern stems from the amoebas’ ability to survive in harsh conditions and bypass routine water treatment processes. These tiny protozoa occur naturally in soil and freshwater and are usually harmless. However, certain species, particularly Naegleria fowleri, widely referred to as the “brain-eating amoeba,” can trigger rare but deadly infections when contaminated water enters the nose during activities such as swimming or diving. This issue is especially significant for India, as Naegleria fowleri causes primary amoebic meningoencephalitis (PAM), a fatal condition that has seen repeated outbreaks in states such as Kerala.What Is Naegleria Fowleri?Naegleria fowleri is a free-living ameba, meaning it is a single-celled organism that survives independently in the environment. It flourishes in warm freshwater sources such as lakes, rivers, ponds, and hot springs. Commonly labelled the “brain-eating ameba,” it earns this name because of its ability to infect the brain and damage brain tissue. The organism is found worldwide in soil and warm freshwater bodies. On rare occasions, it has also been detected in inadequately maintained swimming pools, splash pads, and other recreational water facilities. In some instances, the ameba has even been identified in tap water.According to the US Centers for Disease Control and Prevention (CDC), when water containing the ameba enters the nose and reaches the brain, it can lead to an infection known as primary amebic meningoencephalitis (PAM). In the United States, PAM affects fewer than 10 people each year. Almost everyone diagnosed with PAM does not survive. From 1962 to 2024, 167 cases were reported in the US, with only four known survivors.What Is Primary Amebic Meningoencephalitis?Primary Amebic Meningoencephalitis (PAM) is a rare but almost always fatal brain infection caused by the Naegleria fowleri amoeba, often called the “brain-eating amoeba.” The organism enters the body through the nose from warm freshwater or soil, travels to the brain, and destroys brain tissue. This leads to intense inflammation, confusion, seizures, and, in most cases, death within days of the onset of severe symptoms.Primary Amebic Meningoencephalitis Signs And SymptomsEarly signs of PAM may include headache, fever, nausea, and vomiting. The disease progresses very quickly. Most patients die within one to 18 days after symptoms appear, with coma and death often occurring within five days. As the infection advances, symptoms can worsen to include a stiff neck, confusion, reduced awareness of people and surroundings, loss of balance, and hallucinations.Brain Eating Amoeba Can Thrive In HeatIn a recent perspective published in the journal Biocontaminant, scientists led by Longfei Shu from Sun Yat-sen University explain how climate change, ageing infrastructure, and poor monitoring systems are creating conditions that allow these microbes to spread into areas where they were previously uncommon. Some species are capable of surviving high temperatures and can withstand disinfectants such as chlorine, making them particularly difficult to remove from drinking water supplies and distribution systems.Adding to the concern, free-living amoebas can serve as protective carriers for harmful bacteria and viruses, housing them inside their cells and helping them spread. This so-called “Trojan horse” effect has raised fresh questions about water safety and how pathogens move through the environment, highlighting the need for coordinated, One Health-based approaches.Experts warn that without strong intervention and improved water management policies, free-living amoebas could emerge as a major and largely overlooked threat to global public health in the coming years.