Naegleria fowleri, commonly known as the “brain-eating amoeba,” is a rare but serious single-celled organism. Infections are uncommon but can lead to a devastating illness. This article covers the amoeba’s presence, how infections occur, and prevention strategies.
Understanding Naegleria Fowleri
Naegleria fowleri is a microscopic, single-celled living organism found in warm freshwater environments and soil around the world. It thrives in bodies of water such as lakes, rivers, hot springs, and even poorly maintained swimming pools. The amoeba prefers temperatures up to 115°F (46°C) but can survive in a range of conditions.
This amoeba causes a severe, almost always fatal brain infection known as Primary Amebic Meningoencephalitis (PAM). Once inside the body, it extensively destroys brain tissue, leading to its common nickname. PAM is a rapidly progressing disease of the central nervous system.
Geographic Presence in the United States
Historically, Naegleria fowleri infections have been predominantly reported in southern and southwestern U.S. states, including Florida and Texas. Warmer climates in these regions support the amoeba’s growth, with Texas reporting the highest number of PAM cases since 1962.
While infections remain rare, with fewer than 10 cases annually across the U.S., there is evidence of a northward expansion. Since 2010, infections have been confirmed in northern states like Nebraska, Iowa, Minnesota, Indiana, and Maryland. This shift suggests rising temperatures and increased recreational water use may contribute to PAM’s changing epidemiology.
How Infections Develop
Infections with Naegleria fowleri occur when water containing the amoeba enters the body through the nose. This happens during water activities like swimming, diving, or water sports in warm freshwater. The amoeba then travels from the nasal passages to the brain, causing a severe infection.
Naegleria fowleri cannot cause an infection if swallowed. The amoeba must be forced up the nasal passages with sufficient force to reach the brain. Infections are not spread from person to person.
Practical Prevention Measures
Preventing Naegleria fowleri infection involves taking specific precautions when engaging in water activities. Avoiding recreational water activities in warm freshwater during periods of high water temperature and low water levels can reduce risk. This is especially relevant during the summer months when the amoeba is most active.
When in warm freshwater, holding your nose shut or using nose clips can prevent water from entering the nasal passages. Avoid stirring up sediment in shallow, warm freshwater, as the amoeba can reside in the bottom. Proper chlorination levels in swimming pools are also important, as the amoeba can survive in inadequately treated water.
Recognizing Symptoms and Seeking Care
Initial symptoms of Primary Amebic Meningoencephalitis (PAM) appear within one to twelve days after exposure. These can include severe headache, fever, nausea, and vomiting, often with a stiff neck. As the infection progresses, symptoms rapidly worsen to include seizures, hallucinations, and coma.
Due to PAM’s rapid progression and high fatality rate, immediate medical attention is necessary if these symptoms develop after warm freshwater exposure. Diagnosis can be challenging due to its rarity, but prompt identification and treatment are important.