Brain-Eating Amoeba: How to Protect Yourself During Summer

Naegleria fowleri is a rising healthcare concern worldwide due to global warming. This amoeba causes a rare disease called primary amoebic meningoencephalitis (PAM) — a severe brain infection considered a medical emergency requiring immediate treatment.

Robert F. Kennedy Jr., an independent presidential candidate, has caught the internet’s attention as he claims that some of his health issues, like severe memory loss and mental fog, were caused by a worm — Naegleria fowleri — or, in other words, brain-eating amoeba. In this article, we will introduce you to this amoeba and explain how to protect yourself.

What is a brain-eating amoeba?

Naegleria fowleri is a thermophilic (lives in high temperatures) free-living amoeba commonly known as the 'brain-eating amoeba.' Amoebas are single-cell organisms that can only be seen under the microscope. There are about 50 recognized species of Naegleria and only one, N. fowleri, is confirmed as pathogenic to humans, resulting in primary amoebic meningoencephalitis.

N. fowleri is found in three distinct forms: inactive cyst, transitory flagellate, and trophozoite. When conditions become hostile (for example, cold weather), the amoeba forms an inactive cyst. Because of this transition, N. fowleri can survive during the winter and thrive again in summer. If there is no food around the amoeba but plenty of water, it transforms into a transitory flagellate, meaning it grows extensions for movement. Usually, this form is found during summer when the temperature hits 80–98oF (27–37oC). Finally, when the temperature reaches 95–114oF (35–46oC), they form trophozoites — the only form that can reproduce, eat, form cysts, and cause infection for other organisms.

Where are brain-eating amoebas found?

Naegleria fowleri can be found in warm waters and soil. This amoeba is thermophilic, meaning that the best time for it to grow is at high temperatures (up to 115oF or 46oC) and is especially common in warm equatorial countries (where average annual temperatures are between 59–64ºF/15–18oC). It is essential to mention that this amoeba is not found in salt water. Naegleria fowleri is usually in:

  • Freshwaters, such as warm lakes and rivers
  • Geothermal waters, such as hot springs
  • Untreated swimming pools, water parks, or fountains
  • Drinking water distribution systems
  • Water heaters
  • Untreated geothermal drinking water
  • Warm water discharged from industrial or power plants
  • Soil

How does Naegleria fowleri infect people?

People get infected after water containing N. fowleri enters the body through the nose. From there, the amoeba travels to the brain and infects the brain tissue by causing primary amoebic meningoencephalitis.

Symptoms of brain-eating amoeba

Infected people experience headaches, nausea, fever, fatigue, and vomiting. Later on, stiff neck, irritation, photophobia (sensitivity to light), confusion, seizures, and even coma can occur. The disease progresses rapidly, with different mortality rates reported in scientific literature, but more than 90% of all cases are fatal.

How long until symptoms appear?

PAM usually starts 5–7 days after initial exposure. In some cases, the first symptoms appear after only 24 hours.

How to protect yourself from brain-eating amoeba

In the summer months, avoid activities in warm freshwater places, like lakes, rivers, and hot springs. During water activities in very high temperatures, check if the water doesn’t look scummy or cloudy. This could indicate organic matter in the water, meaning a lot of food for amoebas. When diving, be careful of sediments as they are also places amoebas can be found in.

The good news is, you can keep your head above the water, use nose plugs, or simply hold your nose shut, since the amoeba in the water is only harmful when it enters your body through your nose canals.

In rare cases, N. fowleri can be found in tap water, so you need to sterilize your water by boiling or use distilled water if you are using a neti pot or any other device for cleaning your sinuses.

How common are infections from brain-eating amoebas?

Overall, 381 worldwide cases of PAM were diagnosed from 1962 according to 2021 data. It is considered a rare disease. According to epidemiology studies, 145 cases were diagnosed in the U.S., and the highest numbers of cases by country of origin are the U.S. (41%), Pakistan (11%), and Mexico (9%). It is important to understand that PAM is under-reported, especially in the developing world where weather conditions are warm and favorable for this amoeba to thrive (like Pakistan, India, Nigeria, Nepal, Colombia, and Venezuela).

Various water activities are the main reason for infection. For example, in 143 cases (58% of all related to water), people were swimming or diving, and 10% were waterskiing, wakeboarding, or jet skiing. Of 34 cases associated with swimming pools, 33 happened in 1987 or earlier. The majority of the cases took place during summer.

Due to global warming, the temperature will rise almost everywhere. This amoeba has advantages over other organisms when temperatures are above 86ºF, as higher temperatures provide optimal conditions for its growth while other organisms may not survive or reproduce as effectively as N. fowleri. Moreover, in the U.S. or Australia, incidence of PAM is related to specific seasons, specifically summer. In general, this seasonal link suggests that higher temperatures might increase cases of PAM.

Minnesota is the northernmost U.S. state, in which PAM was ever diagnosed. Since 1962, all confirmed cases of PAM have been limited to the southern states (Arkansas, Arizona, California, Florida, Mississippi, Missouri, Nevada, and others). In 2010, a 7-year-old girl arrived at a local pediatric hospital with unexplained encephalitis, which later was confirmed as PAM. The temperature during August in Minnesota was 38.48ºF above normal, and it was raining more as well (0.7 in above normal). Climate change can impact the expansion of N. fowleri area, meaning doctors in northern areas should consider this amoeba as the cause of meningitis- or encephalitis-related symptoms.

The infections caused by N. fowleri are rare but very serious. This amoeba is found in warm freshwater environments, such as lakes, rivers, or hot springs, and causes PAM when it enters your body through the nose. The best prevention is to avoid freshwaters during hot weather all together or take necessary precautions during swim activities, like making sure to keep your head above water or use nose plugs.


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