The brain-eating amoeba, Naeglaria fowleri
Naeglaria fowleri, popularly known as the “brain-eating amoeba”, is a thermophilic, free-living, single-celled organism in the family Vahlkampfidae. It grows best at a temperature between 25oC and 40oC and is commonly found in soils near warm-water discharges of industrial plants and warm freshwater such as ponds, lakes, rivers, and hot springs, swimming pools.
It also thrives in hot regions in slimy films and sediments of poorly maintained, minimally chlorinated, and/or unchlorinated swimming pools, hence, protection from this organism is imperative.
Etiology
Naeglaria fowleri is the causative agent of the fatal disease called Naegleriasis, which is also known as Primary Amebic Meningoencephalitis (PAM), with a fatality rate of over 97%, meaning once contracted (and due to some factors), it almost always leads to death (CDC, 2017). PAM is a disease of the central nervous system which disproportionately affects males and children, although the reason for this distribution pattern is unclear but may reflect the types of water activities (such as diving or water sports) that might be more common among young boys (Griffin, 1972).
This young girl, Kalie Ann, died from an infection by Naegleria floweri (Image credit: abcnews)
However, infection by the parasite occurs when humans are exposed to the organism via swimming, bathing, or other recreational activity during which water is forcefully inhaled into the upper nasal passages. The Naeglaria fowleri then travels along the olfactory neuroepithelium, passes through the cribriform plate to reach the brain, and leads to brain tissue destruction causing brain swelling, hence the term “brain eating amoeba”.
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According to LiveScience, in 2013, a 12-year-old girl from Arkansas State who contracted naegleriasis was the last person to survive it. She was treated her with a cocktail of anti-fungal medications, and miltefosine, a experimental drug originally used to treat breast cancer but which also had been shown to kill the amoeba in lab experiments.
It takes 1-9 days (average 5 days) for symptoms to appear after nasal exposure to Naeglaria fowleri flagellates. Symptoms include stiff neck, lack of attention, loss of balance, confusion, hallucinations, vomiting and seizure which eventually result to death within two weeks of infection.
Naegleriasis (infection by Naegleria fowleri) is widespread and common worldwide, however, does not occur in oceans and other salt waters. Naegleriasis is a deadly disease. For example, between 1962 and 2015, out of the 140 people that contracted the disease, only 4 survived, implying it has close to 98% fatality. Only recently, another fatal case of a young girl died in Ohio, USA.
A diagrammatic illustration of the etiology of Naeglaria fowleri (Image credit: Livescience)
8 things you must know
Consequently, in order to protect your swimming pools from the risks of Naeglaria fowleri infection, it is imperative to ensure that the following safety precautions are taken:
- Ensure swimming pools are adequately chlorinated and well maintained.
A free chlorine level of 0.5 milligrams per litre (mg/l) (1-3 parts per million range of pools) is said to be effective in killing the amoeba. The pool pH should be maintained at a range of 7.2 to 7.8 thereby inhibiting thriving of the amoeba. The use of rapid pool testing kits may be adopted in order to check the chemistry of the pool before swimming to ensure that it is safe to swim in (Queensland Government, 2017).
- Before discharging into swimming pools, get rid of stagnant water inside the pipelines leading to the pool and ensure that clean and uncontaminated water is discharged into the pool aftermath.
- Since any water body that seasonally exceeds 30oC or continually exceeds 25oC can support the growth of Naeglaria fowleri, it is imperative to ensure that the temperature level of swimming pools water must be kept below this temperature.
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- When you go swimming in warm freshwater, avoid water entering your nose by holding it closed, using nose clips or keeping your head above water, the CDC says.
8 year old Blake Driggers succumbed to an infection by Naeglaria fowleri. He died in 2012
- As the amoeba thrives in sediments, regular vacuuming of the pool is ideal in order to remove slimes and sediments where the parasite may reside. But for effectiveness, the swimming pool must be sun-dried after emptying.
- Dredging is also another method whereby the organic sediment is manually removed from the water body with a dredge. However this method has its drawbacks since some of the sediments may remain in the system.
- Regular check is also advised. Samples of suspected water bodies can be regularly cultured to ascertain the presence or absence of the protozoan, and
- Alternatively, making use of the Clean Flo program which enables the reduction of organic sediments in water bodies by the use of inversion oxidation systems and bioaugmentation is also a reliable method as it continually rids of organic sediments in the water as well as improving the water quality (CLEAN-FLO, 2017).
Written by: Ajeigbe Sheriffdeen K. and Sipho Sibanda and Kunlere Idowu O.
(The trio are volunteers at wastesmart.org).
References
Centers for Disease Control and Prevention (CDC). 2017. “Naegleria fowleri — Primary Amebic Meningoencephalitis (PAM) — Amebic Encephalitis: Illness & Symptoms”. Retrieved June 26, from https://www.cdc.gov/parasites/naegleria/illness.html
Queensland Government. 2017. “Naeglaria fowleri: Qs and As”. Retrieved June 26, from http://conditions.health.qld.gov.au/HealthCondition/condition/14/165/101/Naegleria-fowleri-Qs-As
CLEAN-FLO. 2017. “Reducing the Risk of Naegleria fowleri with CLEAN-FLO”. Retrieved June 27, from https://www.clean-flo.com/naegleria-fowleri/
Griffin JL (1972) . Temperature tolerance of pathogenic and nonpathogenic free-living amoebas. Science. 178 (4063):869-70.
http://afludiary.blogspot.nl/2013/07/arkansas-naegleria-fowleri-shuts-water.html?m=1
https://en.m.wikipedia.org/wiki/Naegleria_fowleri
Others:
https://www.cdc.gov/parasites/naegleria/general.html
http://www.cnn.com/2013/09/12/health/arkansas-amoeba-survivor/index.html
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