In a perspective published in the scientific journal Biocontaminant, researchers describe free living amoebae as an overlooked public health risk that needs far more attention. They point to climate change, aging water infrastructure, and weak monitoring systems as factors that could allow dangerous amoebae to spread and become harder to control.

Why Some Amoebae Are Dangerous

Amoebae are single celled organisms that commonly live in natural environments such as lakes, rivers, soil, and water systems. Most do not harm humans, but a small number can cause severe disease.

One of the best-known examples is Naegleria fowleri, sometimes called the brain eating amoeba. This organism can cause a rare but extremely deadly brain infection when contaminated water enters the nose, often during swimming or other recreational water activities.

"What makes these organisms particularly dangerous is their ability to survive conditions that kill many other microbes," said corresponding author Longfei Shu of Sun Yat sen University. "They can tolerate high temperatures, strong disinfectants like chlorine, and even live inside water distribution systems that people assume are safe."

A Hidden Shelter for Other Pathogens

The danger does not come only from the amoebae themselves. The researchers also warn that amoebae can act as living shelters for other harmful microbes.

Bacteria and viruses can hide inside amoebae, where they may be shielded from disinfectants and other treatment methods. This allows some pathogens to persist longer in drinking water systems and potentially spread more effectively. Scientists refer to this as a Trojan horse effect, and the researchers say it may also play a role in the spread of antibiotic resistance.

Climate Change Could Expand the Risk

Rising global temperatures could make the problem worse. Heat loving amoebae may be able to survive and spread in regions where they were once uncommon, increasing the chance of human exposure.

Recent outbreaks connected to recreational water have already raised concern in several countries. As warm conditions become more widespread, scientists say water managers and health officials may need to prepare for risks that were once considered rare or limited to certain areas.

Researchers Call for Stronger Water Safety Measures

The authors are calling for a coordinated One Health strategy that brings together human health, environmental science, and water management. They say better surveillance, faster diagnostic tools, and more advanced water treatment technologies are needed to reduce the risk before infections happen.

"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."