A July 20 press release from the Nevada Division of Public and Behavioral Health (DPBH) reported the death of a child who’d contracted an infection from a ‘brain-eating ameba’ known as Naegleria fowleri (N. fowleri) after swimming in water from a natural hot spring. The spring,  called Ash Springs, is located in Lincoln County, Nevada.

State public health officials report death from rare brain infection. Nevada Division of Public and Behavioral Health. July 20, 2023.

NBC News identified the child as 2-year-old Woodrow Turner Bundy.

Lenthang M. 2-year-old Nevada boy dies from brain-eating amoeba after visit to hot spring. NBC News. July 21, 2023.

The child fought the infection for seven days before he passed away, according to a Facebook post made by his mother, Briana Bundy.

However, Bundy wasn’t the only person to have died from exposure to the ameba. Earlier this year, the Florida Department of Health reported one death due to Naegleria fowleri—“possibly as a result of sinus rinse practices utilizing tap water.”

Pitt M. FDOH in Charlotte advises community on Naegleria Fowleri infection. Florida Department of Health in Charlotte County. February 23, 2023.

While the pathogenesis is not entirely known, the journal of Clinical and Experimental Pharmacology and Physiology says that the ameba causes “severe destruction of the central nervous system (CNS). The brain damage leads to brain hemorrhage, and death occurs within 3-7 days in undiagnosed cases and maltreated cases.”

Jahangeer M, Mahmood Z, Munir N, et al. Naegleria fowleri: Sources of infection, pathophysiology, diagnosis, and management; a review. Clin Exp Pharmacol Physiol. 2020;47(2):199–212.

The authors of this review on N. fowleri explain that the ameba exhibits two primary pathogenic mechanisms for invading the host’s CNS: contact-independent, causing brain damage through different proteins,  and contact-dependent, causing brain damage through the action of surface structures on the organism called food cups. The food cups are suction cup–like structures used to trap and absorb food. N. fowleri also releases enzymes that destroy cells and nerves.

Tom Skinner, senior public affairs officer at the CDC, tells MDLinx.com that infection from N. fowleri is rare but often fatal. The mortality rate is said to be between 95% and 99%, according to the review article authors. Skinner says that number is more like 97%, as only four out of 157 known infected patients between 1962 and 2022 have survived. 

However, since 2013, only 29 cases were reported in the United States. Last year, three confirmed cases were reported—all of which occurred after freshwater exposure in Iowa, Nebraska, and Arizona, the CDC says.

Naegleria fowleri — Primary Amebic Meningoencephalitis (PAM) — Amebic Encephalitis. Case report data & graphs. Centers for Disease Control and Prevention. May 3, 2023.

Who is most at risk of contracting Naegleria fowleri?

CDC data shows that the majority of cases from 1962-2022 occurred from exposures in ponds, lakes, and reservoirs in July and August—mostly in boys under the age of 19. “It thrives in heat,” Skinner says. 

And while N. fowleri has historically been found in the Southern states; Skinner says that its direction may be expanding, “possibly due to climate change.” In 2010, an infection was found in Minnesota; Skinner says—600 miles farther north than the first reported case. Now, the ameba has been found in Maryland, Iowa, and Indiana, suggesting that it’s not only people in the Southern states who are at risk. 

It’s worth noting that a 2020 article in Trends in Parasitology found that N. fowleri may be transmitted not only through water but also through soil or dust as a “possible alternative route.”

Maciver SK, Piñero JE, Lorenzo-Morales J. Is Naegleria fowleri an emerging parasite? Trends Parasitol. 2020;36(1):19–28.

The authors, who looked at the ameba’s impact on the Indian subcontinent (ISC), found that the epidemiology between the Southern states in the United States and the ISC differs—noting that patients with PAM in the ISC are older and may have contracted the infection not through water. 

Additionally, they echo the CDC’s suggestion that the spread may be due to climate shifts: “We show that PAM is under-reported and argue that climate change will increase the incidence of PAM and that the geographic range of N. fowleri will spread polewards,” they write. 

Researchers are still trying to understand how the ameba spreads exactly. “Despite the expansive distribution of N. fowleri,” the Trends in Parasitology authors say, “its presence seems sporadic and does not consistently overlap with PAM occurrences, hinting at a complex interaction of ecological abiotic and biotic factors.”

What about drinking water that is contaminated with N. fowleri? Research published in FEMS Microbiology Ecology says that the United States does not routinely test recreational waters for the ameba and is not currently subject to EPA drinking water regulations.

Stahl LM, Olson JB. Environmental abiotic and biotic factors affecting the distribution and abundance of Naegleria fowleri. FEMS Microbiology Ecology. 2021;97(1):fiaa238.

However, it is listed as a contaminant by the US Environmental Protection Agency (EPA). That said, worried patients should be reminded that an infection is rare. 

Signs and symptoms of PAM from N. fowleri

According to the CDC, fever, headache, nausea, or vomiting can be symptoms of PAM—usually starting about five days after exposure (although symptoms can occur anytime between one and 12 days after nasal inhalation). Additional later symptoms include a stiff neck, confusion, lack of attention to people and surroundings, loss of balance, seizures, and hallucinations. The infection is not contagious. 

Skinner notes that PAM is often misdiagnosed as bacterial meningitis—which the journal Clinical and Experimental Pharmacology and Physiology says may have something to do with the low mortality rate. 

Skinner says that patients should seek medical care if they have symptoms and have recently been in warm fresh water. 

Preventing and treating infection

For people employing sinus rinses, such as with neti pots, the Florida Department of Health advises using only distilled or sterile water. If tap water is used, it should be boiled for at least one minute and cooled before sinus rinsing.

Treatment for PAM, according to the CDC, may consist of a combination of drugs, including amphotericin B, azithromycin, fluconazole, rifampin, miltefosine, and dexamethasone.

Naegleria fowleri — Primary Amebic Meningoencephalitis (PAM) — Amebic Encephalitis. Treatment. Centers for Disease Control and Prevention. May 3, 2023.

The CDC recommends healthcare providers suspecting an infection contact the CDC Emergency Operations Center at 770-488-7100 to consult with a CDC expert.