The Sligo Water System, which serves part of south Bossier Parish in North Louisiana, is working to eliminate the presence of Naegleria fowleri amoeba.
The single-celled microbe can live around the world. It loves heat and thrives during warmer months. The amoeba can enter the nose during water-related activities, like swimming or using a neti pot, according to information from the Centers for Disease Control and Prevention, but this is rare.
Once in the nose, the amoeba can travel through nasal tissue and olfactory nerves to the brain and cause primary amebic meningoencephalitis (PAM). Once the amoeba reaches the brain after passing through the cruciform plate in the skull, it begins to destroy brain tissue.
People cannot be infected by drinking water with Naegleria fowleri, and it has not been shown to spread from water vapor or droplets like in the shower or from a humidifier.
Am I likely to get it?
According to the CDC, the disease is rare but usually fatal. In the U.S. 143 infections with four survivors have been reported from 1962 to 2017.
More than 75 percent of those cases were in males, and 120 of the total cases were in children and adolescents, most commonly ages 10-14.
Up to eight infections are reported each year, and higher numbers correlate with heat wave years. (The Rare Disease Act of 2002 defined a rare disease as one affecting less than 200,000 in the U.S.)
Most of those infections were in southern states, and more than half were in Texas and Florida. Water sampling shows the amoeba is common in many lakes in southern states during warm months. It can live in lakes, rivers, hot springs, warm water discharge from plants, water heaters, poorly maintained pools and soil.
Six infections in the U.S., according to the CDC, were associated with water from drinking water systems, use of a slip-n-slide, immersing the head in the bathtub or nasal rinsing.
From 2008 to 2017, 34 infections were reported in the U.S., according to the CDC. Of those:
- 30 were infected by recreational water,
- 3 were infected after rinsing their sinuses with infected tap water and
- 1 person was infected on a backyard slip-n-slide.
The first PAM infections were reported in the 1960s, and the ameoba was a new species, but investigations in archived autopsy tissue samples proved that it was an issue in the U.S. as early as 1937.
Transplantation of organs from infected donors has been documented; the recipients were not infected. In autopsy findings from two deceased PAM cases, Naegleria fowleri was found in the lung, kidney, heart, spleen and thyroid.
Multiple researchers have noted that the number of people potentially exposed to Naegleria fowleri is significantly greater than the number of reported PAM cases.
Millions of people swim in the U.S. every summer, but usually fewer than eight cases of PAM are reported each year. That makes it difficult to tell people how to reduce their risks.
What are the symptoms?
Symptoms of PAM are similar to those of bacterial meningitis, which is also serious and potentially deadly. They start 1-9 days after exposure to Naegleria fowleri, and the disease can progress rapidly. Patients die 1-18 days after symptoms begin.
Stage 1:
- severe frontal headache
- fever
- nausea
- vomiting
Stage 2:
- stiff neck
- seizures
- altered metal status
- hallucinations
- coma
To treat PAM, the protocol used to save two of the four U.S. survivors was to lower the body temperature well below normal levels to combat brain swelling and killing the amoeba with a drug called miltefosine. The aggressive treatments were used quickly, and both patients had full neurologic recovery.
Because it's so rare, about 75 percent of diagnoses are made after the patient's death. A laboratory finds Naegleria fowleri organisms, nucleic acid or antigen in cerebrospinal fluid, biopsy or tissue specimens.
About the amoeba
According to the CDC, Naegleria fowleri has three stages in its life cycle and is only infective during the trophozoite stage. Trophozoites and flagellated amoeba have been found in brain tissue and cerebrospinal fluid.
Chlorine and monochloramine are commonly used to treat drinking water and swimming pools. Naegleria fowleri is moderately sensitive to chlorine. It has not been detected in sea water.
When conditions are unfavorable, like food supply or temperatures being too low, it can revert to a cyst stage and change back to the trophozoite stage when the environment is better. Cysts are not found in brain tissue.
The amoeba grows best at temperatures up to 115 degrees Fahrenheit. At all stages in the life cycle, Naegleria fowleri can survive up to 149 degrees, and the cysts can survive for months at temperatures above freezing.
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