In people infected with Naegleria fowleri, the primary cause of death is not always the amoeba itself as commonly believed — in some cases, the body’s immune response can play an even more destructive role.
Around Lake Mead in the U.S. state of Nevada, warning signs have been placed near certain waters fed by more than 300 hot springs, cautioning that these waters may contain the amoeba Naegleria fowleri. This microscopic, single-celled organism can enter the human body through the nose, travel to the brain, and cause a deadly infection.
On July 9, 2014, just a few days after swimming in Lake Minnewaska in Minnesota, 14-year-old Hunter Butain died. Doctors believed the cause of his death was this dangerous water-dwelling parasite. Among the public, the organism is more commonly known as the “brain-eating amoeba.”
Approximately 97 percent of people infected with this organism do not survive. However, experts note that this name does not fully explain why the disease is so deadly and can be somewhat misleading.
Does the amoeba really “eat the brain”?
In a process that sounds like something out of a horror movie, Naegleria fowleri enters through the nasal cavity and migrates toward the brain along the olfactory nerve. This is where the most severe damage begins.
However, scientist M. Baig and other researchers argue that the primary cause of death is not solely the amoeba’s direct attack. According to them, an excessively strong immune response by the body significantly worsens the condition.
Baig explained this theory in an article published in the August issue of the journal Acta Tropica. Laboratory studies have shown that in the absence of immune cells, N. fowleri requires approximately eight hours to cause serious damage to the cells of human blood vessels. This finding highlights the decisive role of the immune system in the progression of the disease.
Where is the risk higher, and who is most vulnerable?
Naegleria fowleri typically causes a rare but extremely severe brain infection in otherwise healthy individuals — most often children and adolescents. The medical term for this disease is primary amoebic meningoencephalitis (PAM).
This disease is extremely rare:
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Between 1962 and 2014, only 133 cases were recorded in the United States, according to the CDC.
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Most cases occurred in southern U.S. states.
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Due to the difficulty of diagnosis, the actual number of cases may be higher.
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Experts note that climate change may be allowing the amoeba to spread northward.
Symptoms and diagnostic challenges
Early symptoms of infection typically include:
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severe headache
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high fever
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nausea and vomiting
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changes in the sense of smell
Because the disease is so rare, timely diagnosis is extremely difficult.
Jesús Serrano-Luna, a cell biologist at the National Polytechnic Institute of Mexico, explains that the amoeba releases proteins that damage tissues and trigger severe inflammation in brain tissue.
Is survival possible?
Scientists believe that the main goal of treatment should not only be to destroy the amoeba but also to control inflammation and swelling in the brain.
A real-life example occurred in 2013, when 12-year-old Kali Hardig became one of the very few people to survive this deadly infection.
CDC epidemiologist Jennifer Cope stated:
“It was astonishing. Kali was the first person in the United States to survive this disease in the past 35 years.”
Several factors contributed to Kali Hardig’s survival:
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very early diagnosis
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the use of a new-generation anti-amoebic drug
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aggressive reduction of brain swelling and intracranial pressure
Cope explains it this way:
“Our skull normally protects us. But when severe brain swelling occurs, that rigid structure can actually become dangerous.”
Conclusion
Infection with Naegleria fowleri triggers a domino effect:
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the amoeba enters the brain
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intense inflammation begins
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brain tissue swells
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pressure increases and vital functions are disrupted
For this reason, the term “brain-eating amoeba” is partly accurate but does not tell the whole story. New scientific evidence shows that the body’s own defense mechanisms also play a critical role in the development of a fatal outcome.