The brain eating amoeba Naegleria fowleri remains extremely rare in the United States, but two fatal infections reported in Louisiana and North Carolina during August 2026 have renewed attention on the dangers of warm freshwater exposure. The CDC says 180 U.S. cases of primary amebic meningoencephalitis (PAM) were diagnosed from 1937 through 2025, with no more than eight cases recorded in any single year.
The latest North Carolina investigation also identified a likely exposure location. State health officials said a water feature at a Durham community organization was the most likely source of a teenager’s infection. Testing by the CDC detected Naegleria fowleri DNA in water from the feature, which remains closed.
What Is Naegleria Fowleri?
Naegleria fowleri is a microscopic, free-living amoeba that naturally occurs in soil and warm freshwater. It can live in lakes, ponds, rivers and hot springs. In rare circumstances, it can also be found in inadequately maintained recreational water or contaminated tap water.
The organism becomes dangerous when water containing the amoeba enters the nose. From there, it can travel to the brain and cause PAM, a rapidly progressing infection that destroys brain tissue.
Swallowing contaminated water does not cause PAM. The infection also does not spread from one person to another.
The risk to an individual swimmer remains very low. The CDC generally reports fewer than 10 PAM cases in the United States each year.
Latest U.S. Cases in 2026
Two fatal cases have received significant attention during the latest summer reporting period.
In Louisiana, health officials confirmed in August that a resident had contracted Naegleria fowleri. The Louisiana Department of Health said the infection was likely acquired while swimming in Lake Claiborne in north Louisiana. The patient was later identified by her family as Lillian Smart, an 8-year-old girl from Ruston. She died on August 22, shortly after her eighth birthday.
Louisiana health officials said the state had not recorded a confirmed infection since 2013. The department also emphasized that the organism occurs naturally in warm freshwater and that routine environmental testing for Naegleria fowleri is not conducted in recreational bodies of water.
A separate case involved a North Carolina teenager who died on August 31. The investigation later focused on a water feature at El Futuro, a community-based organization in Durham.
NCDHHS said investigators interviewed the teenager’s family about possible freshwater exposures. Several locations were investigated and tested with assistance from the CDC. The findings did not conclusively establish the exposure site, but officials determined that the Durham water feature was the most likely source.
The teenager had reportedly interacted with the feature during the potential exposure period, including splashing water onto the face. The feature was closed on August 28. CDC testing later detected Naegleria fowleri DNA in water from the site.
These two cases occurred within weeks of each other, but they do not indicate widespread transmission. PAM remains an exceptionally uncommon infection in the United States.
Why Warm Freshwater Creates a Risk
Naegleria fowleri thrives in warm freshwater. The organism grows best at higher temperatures, and health officials have historically associated infections with hot summer conditions.
CDC data show that 157 of the U.S. PAM cases from 1937 through 2025 had a known month of illness onset. July and August accounted for the largest share, a pattern that may reflect both warmer water and increased recreational exposure during summer.
The amoeba grows at temperatures that can become common in shallow freshwater during hot weather. North Carolina officials said Naegleria fowleri grows best at higher temperatures, with growth possible up to about 115°F.
Most infections have historically occurred in southern states. However, CDC data show that cases have also occurred farther north, including states such as Nebraska, Iowa, Minnesota, Indiana, Maryland and northern California since 2010.
That geographic history does not mean every warm lake contains the organism. It does mean that temperature alone cannot be used to determine whether a particular body of water is safe.
How Infection Happens
PAM generally develops after contaminated freshwater enters the nose. Activities that can force water into the nasal passages can therefore create exposure.
Examples include:
- Swimming in warm freshwater lakes.
- Diving or jumping into freshwater.
- Water-skiing and similar activities.
- Playing in untreated or inadequately treated recreational water.
- Getting contaminated water into the nose during recreational play.
- Using contaminated water for nasal or sinus rinsing.
The CDC specifically advises people to use distilled or sterilized water, or tap water that has been boiled and cooled, when rinsing the sinuses or nasal passages.
There is an important distinction between exposure and infection. Even when Naegleria fowleri is present, infection remains extremely rare. The organism must enter through the nose and reach the brain for PAM to develop.
The CDC also states that people cannot contract PAM by swallowing water containing the amoeba. Properly maintained and disinfected swimming pools are not considered a typical source of infection.
Symptoms of PAM
The symptoms can initially resemble other serious infections, including bacterial meningitis. That similarity can make early recognition difficult.
According to the CDC, early symptoms can include:
- Severe headache
- Fever
- Nausea
- Vomiting
Symptoms generally begin about five days after exposure, although the reported range is one to 12 days. Once symptoms appear, the illness can progress rapidly.
Later symptoms can include:
- Stiff neck
- Confusion
- Problems paying attention
- Loss of balance
- Hallucinations
- Seizures
- Coma
The CDC says death typically occurs around five days after symptoms begin, although the reported range is one to 18 days.
Anyone who develops sudden fever, headache, vomiting or stiff neck after recent exposure to warm freshwater should seek emergency medical care immediately. Early communication about the water exposure can help healthcare professionals consider PAM during diagnosis.
How Doctors Diagnose the Infection
Doctors diagnose PAM through laboratory testing. Because the infection is so rare, healthcare providers may not immediately suspect Naegleria fowleri when a patient first becomes ill.
The CDC notes that testing for the infection is available at only a limited number of laboratories in the United States, including CDC laboratories. Diagnosis can sometimes occur only after a patient has died.
The rapid progression of the disease makes early recognition especially important. A recent history of swimming or other exposure to warm freshwater can provide an important clue.
Treatment for Naegleria Fowleri Infection
There is no single medication that guarantees recovery from PAM. Treatment involves a combination of medicines and intensive medical care.
CDC clinical guidance recommends combination therapy for confirmed or suspected infections. Treatment regimens have included drugs such as amphotericin B, azithromycin, fluconazole, rifampin, miltefosine and dexamethasone.
A small number of people have survived PAM. The CDC’s current clinical guidance identifies five well-documented survivors in North America.
Because the disease progresses quickly, suspected cases require urgent specialist involvement. CDC assistance is available to clinicians for diagnostic testing, specimen collection and treatment recommendations.
How to Reduce the Risk
The CDC recommends several practical precautions for people entering warm freshwater.
People can reduce exposure by:
- Holding the nose shut or wearing a nose clip when jumping or diving into freshwater.
- Keeping the head above water when entering hot springs.
- Avoiding stirring up sediment in shallow freshwater.
- Avoiding activities that force untreated freshwater into the nose.
- Using only distilled, sterile or properly boiled and cooled water for sinus rinsing.
The CDC recommends assuming that Naegleria fowleri could be present in warm freshwater because routine testing cannot reliably establish that a lake, river or pond is free of the organism.
For nasal rinsing, ordinary tap water should not be used unless it has been appropriately treated. Distilled or sterilized water provides a safer option, while boiling and cooling tap water can also eliminate the relevant organisms.
What the Latest 2026 Cases Show
The recent Louisiana and North Carolina cases demonstrate that exposure does not have to involve a large natural lake.
Louisiana’s case was associated with likely exposure at Lake Claiborne. North Carolina’s investigation instead focused on a constructed water feature at a community organization. The two investigations involved different settings, but both involved warm freshwater exposure.
The North Carolina investigation is particularly notable because investigators tested multiple potential exposure sites. Officials said the Durham water feature was the only investigated location that produced Naegleria fowleri DNA, although they stopped short of saying the testing conclusively proved where the infection occurred.
The feature remains closed to the public. El Futuro said it is cooperating with public health officials following the testing results.
These findings reinforce the importance of preventing untreated warm freshwater from entering the nose, especially during periods of high temperatures.
How Common Is the Brain Eating Amoeba Infection?
Despite the attention surrounding individual cases, PAM is extraordinarily rare.
CDC surveillance shows 180 diagnosed U.S. cases from 1937 through 2025. Annual totals ranged from zero to eight cases. The CDC’s updated data also show that males, particularly boys and teenagers, have accounted for a disproportionate share of reported cases.
Among males, the 10-to-14 age group had the highest number of recorded cases, with 45 cases in the CDC dataset. Researchers have not established a definitive reason for the difference, although water-related activities may contribute to exposure patterns.
The rarity of the infection is important context. The presence of Naegleria fowleri in the environment does not mean that everyone exposed to the same water will become infected.
The Latest Status in the United States
As of the latest update, public health agencies continue to describe Naegleria fowleri infection as rare but extremely serious. The most recent national CDC data document 180 U.S. PAM cases through 2025, while the two fatal cases reported in Louisiana and North Carolina occurred during 2026.
The North Carolina investigation has also provided a recent example of how public health authorities respond after a suspected exposure. Officials identified possible exposure locations, collected environmental samples, worked with CDC specialists and closed the location that produced the relevant testing result.
For swimmers, the central prevention message remains straightforward: avoid getting warm untreated freshwater into the nose, and use safe water for sinus rinsing.
Stay informed about the latest U.S. cases and public health findings as officials continue monitoring this rare but serious infection.