The Brain-Eating Amoeba and Primary Amoebic Meningoencephalitis

During my childhood, I developed a keen fascination for studying deadly diseases. One particular organism that caught my attention was the brain-eating amoeba. Contrary to its non-pathogenic nature, this voracious protozoan targets humans as hosts and feeds on their brains, living up to its name.

Today, I'd like to discuss Primary Amoebic Meningoencephalitis, a disease caused by Naegleria fowleri, more commonly known as the brain-eating amoeba. You might be shocked to learn that activities like swimming or engaging in aquatic pursuits, which involve water passing through your nostrils, can put you at a high risk of infection. It's important to note that this risk is not limited to untreated pools, as the amoeba can be found in various untreated water bodies.

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This amoeba has a peculiar affinity for the human brain, feeding on its tissue and compromising our defense mechanisms. Naegleria fowleri is one of the smallest lifeforms on Earth, capable of devouring bacteria and other creatures. It exists in different stages, including the cyst, flagellated, and trophozoite stages, with the trophozoite stage being the predominant one. While it can be present in ponds, lakes, warm springs, pools, wells, and tap pipes, it cannot survive in saltwater or properly chlorinated water. So, if your pool is adequately treated, it is safe. Similarly, you can trust that the Earth's five oceans are generally safe as well. The amoeba's flagella enable it to survive and move efficiently.

While water contaminated with Naegleria fowleri can be swallowed from the mouth, it becomes a problem when it goes in from the nostrils. Let me state that a brain eating amoeba is not a prokaryote or a virus but rather a eukaryote but it is a unicellular protozoan. It's not like when water gets into your nostrils, you get brain-eating amoeba, at least not all of us have one eukaryotic protist eating up our brain because water ran through our nose. A lot of us have gotten water up our noses and we haven't been infected by brain-eating amoeba.

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For Naegleria fowleri to cause Primary Amoebic Meningoencephalitis, the infested water must reach the cribiform plate, where the olfactory nerves are located. Now, if you become concerned about drinking water containing Naegleria fowleri, let me put your mind at ease. When the amoeba is swallowed, stomach acid kills it, rendering it harmless. However, when it attaches to the olfactory epithelial tissues, it transforms into its trophozoite form, assuming its amoebic nature.

When Naegleria fowleri is in its flagellated stage, it is harmless and just moves around with its flagella but when it gets to the trophozoite stage, it becomes harmful because, at that stage, it is at its feeding phase where it begins to feed on olfactory nerve fibers because they detect acetylcholine and have receptors for acetylcholine. it keeps eating and going toward the brain until it reaches the cranial cavity. The Amoeba engulf cells that it wants to eat so it can be easy to digest them. When the amoeba gets to the brain, it begins to consume engulf and eat the brain neurons. When the brain notices this, it begins to send signals to the body causing body functions to be compromised.

Over time, the brain cells affected by Naegleria fowleri undergo necrosis, leading to inflammation due to the release of necrotic enzymes and subsequent information relayed to the body. The presence of the amoeba in the brain causes seizures, tremors, impaired nerve signaling, as well as inflammation of the meninges and brain tissue. As the brain inflames, brain cells expand, and fluid accumulates in the cranial cavity.

While certain parts of the brain can withstand this attack, the brainstem is particularly vulnerable. The brainstem controls vital functions such as breathing and heart rate. Thus, if the brainstem suffers an attack, the patient becomes at high risk of fatality. I don't mean to alarm you with talk of fatality, as it's possible to survive an infection, but the time from infection to death is typically around 12 days. Unfortunately, successful treatment is rare due to the difficulty in diagnosing the infection. Naegleria fowleri mimics viral and bacterial meningitis, making it a challenging condition to identify accurately.

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Reference

https://www.cdc.gov/parasites/naegleria/index.html
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10210555/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9964342/
https://www.ncbi.nlm.nih.gov/books/NBK430754/
https://bmcinfectdis.biomedcentral.com/articles/10.1186/s12879-021-06932-9