Brain-Eating Amoeba: Why Your Body is No Match This Microorganism

Naegleria fowleri, also referred to as brain-eating amoeba, is a single-celled microorganism that can be extremely fatal to humans despite its microscopic size. Although the infection it causes, a brain disease known as primary amoebic meningoencephalitis (PAM), is rare, has a fatality rate exceeding 97% (Cleveland Clinic, 2022). This amoeba continue to alarm scientists, especially as new information about it emerges regularly. The most common route of infection is through the nasal passages, after which the organism migrates to the brain; infection cannot occur from swallowing contaminated water. Once N. fowleri enters into the body and PAM develops, the immune system struggles to combat it, often proving ineffective against the infection. 

Brain-eating amoeba thrives in very warm fresh water environments, such as lakes, hot springs and even rivers (Cleveland Clinic, 2022). It can also be present in untreated tap water and poorly chlorinated swimming pools. PAM occurs when contaminated water forcefully enters the nose during activities like water skiing, diving, or other water sports (Sreenivas, 2024). Once inside the nasal cavity, the amoeba travels along the olfactory nerve (the nerve responsible for the sense of smell) and makes its way to the brain. There, it bypasses the body’s immune defenses and begins to inflict severe and irreversible damage. 

Primary amoebic meningoencephalitis (PAM) is the disease caused by brain-eating amoeba, but interestingly, not all encounters with N. fowleri result in this condition, and the organism may be more common than we realise. According to WebMD, studies have shown that many 

individuals have antibodies to the amoeba, suggesting they were exposed but their immune systems successfully fought it off. However, it remains unclear whether N. fowleri enters the body and always causes PAM which is almost always deadly, or infects the body and only rarely causes PAM. Symptoms of PAM appear within two to fifteen days after exposure, and include intense headaches, high fever, nausea, vomiting, stiff neck, trembling, mental confusion, and even coma (Cleveland Clinic, 2022). PAM progresses rapidly, and death usually occurs within three to seven days after symptoms begin (Sreenivas, 2024). 

The human immune system is largely ineffective against N. fowleri, as the organism is able to bypass both the body’s primary and secondary line of defense. Once the amoeba reaches the olfactory bulbs in the brain, it begins consuming the tissues there, which triggers an immune response. Inflammation follows as immune cells attempt to attack the invader, leading to early symptoms, such as headaches, nausea and vomiting. As the amoeba penetrates deeper into the brain tissue, secondary symptoms occur, like seizures and confusion. Interestingly, death is not typically caused by the direct destruction of the brain matter, but rather by the extreme inflammation and swelling triggered by the immune system’s efforts to combat the infection (Jacobson, 2014). 

In conclusion, although infection by PAM is rare, public awareness and preventative measures are essential, especially as global temperatures rise and climate change creates more favourable conditions for N. fowleri. To reduce the risk of infection, individuals should take precautions such as wearing nose clips during water activities to prevent water from being forcefully pushed into the nasal passages. Additionally, when using devices like neti pots for nasal irrigation, it is recommended to use only sterile or filtered water, specifically filters with a pore size of 1 micrometer or smaller (Sreenivas, 2024). Taking steps like these can help protect against one of the deadliest microorganisms known to science. 

References 

● Brain-Eating Amoeba. (2022, November 29). Cleveland Clinic. https://my.clevelandclinic.org/health/diseases/24485-brain-eating-amoeba. Retrieved on July 29th, 2025. 

● Jacobson, R. (2014, July 18). What happens when an amoeba “Eats” your brain? Scientific American. 

https://www.scientificamerican.com/article/what-happens-when-an-amoeba-eats-your -brain/. Retrieved on July 29th, 2025. 

● Sreenivas, S. (2024, December 3). Brain-Eating Amoeba. WebMD. https://www.webmd.com/brain/brain-eating-amoeba. Retrieved on July 29th, 2025.