Discover the dangers of Naegleria Fowleri, a brain-eating amoeba, and learn how to protect yourself on Meri Sehat.

Naegleria Fowleri

Naegleria fowleri, commonly known as the "brain-eating amoeba," is a rare but highly dangerous microorganism that can cause severe infection in humans. The symptoms of Naegleria fowleri infection are often nonspecific in the early stages, making it challenging to diagnose. However, as the infection progresses, distinct symptoms may arise. Initially, individuals may experience a sudden onset of headache, fever, and nausea, which can easily be mistaken for common ailments. As the naegleria virus infiltrates the central nervous system, the symptoms rapidly worsen. Victims may develop a stiff neck, sensitivity to light, and a change in their sense of taste or smell. Confusion, seizures, and hallucinations may also occur. Unfortunately, the infection progresses rapidly, and without prompt treatment, it can lead to devastating consequences, including brain damage and even death. It is crucial to recognize the early symptoms of Naegleria fowleri infection and seek immediate medical attention

A. JABBAR DENTAL CLINIC KARACHI

Sadia Khan

Overview

Naegleria fowleri, also known as the brain-eating amoeba, is responsible for causing a rare but severe brain infection called primary amebic meningoencephalitis (PAM).&nbsp; 
&nbsp;

Naegleria fowleri is a single-celled organism commonly found in warm freshwater bodies like lakes and rivers, and soil. The thermophilic amoeba survives by feeding on bacteria and fungi in warm waters, growing best at high temperatures of up to 45 degrees Celsius[4]. Humans contract the infection when warm freshwater enters the nose; the amoeba travels to the brain through the cribriform plate, resulting in primary amebic meningoencephalitis (PAM).

Named after the Australian pathologist Malcolm Fowler, Naegleria fowleri first came to light in Australia when the virus was isolated from primary amebic meningoencephalitis infections[1]. Soon after, in 1966, infections began being reported in the United States. According to the Centers for Disease Control and Prevention (CDC), 145 cases of PAM have been reported in the United States since 1962[2]. A majority of these cases resulted from swimming in infested freshwater bodies, primarily in the summer months.

Globally, an estimated 440 cases of PAM due to Naegleria were reported until 2008<a href="#accordion">[3]</a>. Other than the United States, cases have also been reported in Australia, Great Britain, Mexico, Czech Republic, Nigeria, New Zealand, and India.

Pakistan reported its first case in 2008<a href="#accordion">[5]</a>. Since then, hundreds of cases have been reported across the country, with the majority of cases occurring in Karachi<a href="#accordion">[6]</a>. The city alone reported 146 cases until October 2019<a href="#accordion">[5]</a>. Naegleria cases in Pakistan mainly occur in summer and before the monsoon seasons<a href="#accordion">[5]</a>. 
&nbsp;

Recently researchers tested drinking water supplies from different areas of Karachi. N. fowleri was present in 8% of the samples<a href="#accordion">[8]</a>. Researchers link the presence of the amoeba in tap water to poor water disinfection, old plumbing, use of water storage tanks, poor tap water hygiene, and environmental settings<a href="#accordion">[8]</a>. There is evidence to believe that the domestic water supply in the city contains N fowleri<a href="#accordion"> [5]</a>, which is interesting since Karachi&rsquo;s water is normally saline and Naegleria does not survive in such conditions. This suggests that the Naegleria strain currently circulating in the city has likely developed resistance against saline conditions, or that is different from the strain found in other parts of the world<a href="#accordion">[5][7]</a>.

With the ongoing climate change causing extended summers and increased humid conditions, the disease burden is likely to increase further in the country and around the world. 
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There are no subtypes of Naegleria fowleri. 
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Signs and Symptoms

Once the parasite enters the brain through the cribriform plate, it results in primary amoebic meningoencephalitis (PAM). The incubation period is between 1 to 14 days. Patients typically have a sudden onset of severe symptoms that often mimic viral meningitis. These include: 
&nbsp;

<ul>
	<li>Fever</li>
	<li>Severe <a href="https://merisehat.pk/disease/migraines-73">headache</a></li>
	<li>Nausea and vomiting</li>
	<li>Photophobia</li>
	<li>Stiff neck</li>
	<li>Seizures</li>
	<li>Hallucinations</li>
	<li>Mental confusion</li>
	<li>Coma 
	&nbsp;</li>
</ul>

Causes

The brain-eating amoeba enters the brain through the nasal cavity. Activities such as swimming or diving in lakes and rivers can cause Naegleria to enter the central nervous system (CNS). In rare cases, infections have also occurred from swimming in pools or surf parks with not enough chlorine. Certain practices, such as the use of neti pots for nasal irrigation can also cause the disease, if care is not taken to ensure that the water being used is distilled or sterile. 
&nbsp;

Interestingly, the majority of cases in Pakistan result from ablution with water containing the amoebae[5][8], indicating the need for improving water disinfection and tap water hygiene.

It is important to note that drinking contaminated water does not contribute to the disease. Moreover, the infection is not contagious and cannot spread from person to person. 
&nbsp;

There are no screening tests for Naegleria. 
&nbsp;

Diagnosis

In people with a history of swimming in warm freshwater bodies or suspected of having PAM, doctors will conduct the following tests: 
&nbsp;

<ul>
	<li>Lumbar Puncture - Samples of the cerebrospinal fluid are taken and assessed for the presence of the amoeba with the help of PCR testing.</li>
	<li>MRI Or CT Scan - These brain scans provide a detailed image of the brain and help look for hemorrhages or infarctions.</li>
	<li>Brain Biopsy - A sample of the brain is examined under a microscope for the presence of the amoeba. 
	&nbsp;</li>
</ul>

At times, cases are diagnosed on an autopsy performed after the patient&rsquo;s death. 
&nbsp;

Treatment

A combination of intravenous or intrathecal medications is used to treat Naegleria. These include amphotericin B, miltefosine, azithromycin, rifampin, fluconazole, and dexamethasone<a href="#accordion">[4]</a>. Furthermore, the use of therapeutic hypothermia and management of cerebral edema has led to survivors with complete neurological recovery<a href="#accordion">[4]</a>. 
&nbsp;

The prognosis for Naegleria infection is extremely poor, with a mortality rate above 95%<a href="#accordion">[3]</a>. Death usually occurs within 5 days of onset of symptoms, due to brain swelling.

&nbsp;

The following factors increase the risk of contracting Naegleria: 
&nbsp;

<ul>
	<li>Swimming in warm freshwater bodies, such as lakes and rivers</li>
	<li>Hot springs</li>
	<li>Poorly maintained swimming pools</li>
	<li>Using undistilled or non sterile water for ablution or nasal irrigation 
	&nbsp;</li>
</ul>

No vaccine is currently available for Naegleria. However, the following measures can help prevent contracting the disease: 
&nbsp;

<ul>
	<li>Avoiding swimming in warm still waters, especially during late summer.</li>
	<li>Wearing a nose clip when swimming, diving, or doing other water-related recreational activities.</li>
	<li>Using distilled or sterile water for ablution or the neti pot.</li>
	<li>Ensuring swimming pools are properly disinfected with chlorine.</li>
	<li>Using chlorine tablets for water storage tanks at homes and mosques. 
	&nbsp;</li>
</ul>

Doctors often prescribe Amphotericin B to treat Naegleria fowleri. However, since it cannot cross the blood-brain barrier, the medicine is ineffective. Therefore, a team of Spanish researchers recently explored the use of a traditional medicinal plant for the brain-eating amoeba<a href="#accordion">[9]</a>. 
&nbsp;

They first created an ethanol extract from the leaves of the plant. Next, they isolated and tested various compounds from the extract to detect the most potent one. Inuloxin A was found to be the most potent at killing the amoeba in the lab study. The compound not only disrupted the membranes but also caused oxidative damage, leading the parasites to undergo apoptosis. Although it was less potent when compared to Amphotericin B, the compound has a higher potential of crossing the blood-brain barrier.

The researchers suggest further studies to confirm these findings. Nevertheless, the lab study provides significant data for the development of new treatments for primary amoebic meningoencephalitis (PAM) caused by Naegleria fowleri. 
&nbsp;

Key Points

<ul>
	<li>Naegleria fowleri is a brain-eating amoeba primarily found in freshwater bodies, such as rivers, lakes, and hot springs.</li>
	<li>It is responsible for causing a rare but severe brain infection called primary amebic meningoencephalitis (PAM).</li>
	<li>The brain-eating amoeba enters the brain through the nasal cavity.</li>
	<li>Activities such as swimming or diving in lakes and rivers can cause Naegleria to enter the central nervous system (CNS).</li>
	<li>Signs and symptoms are similar to that of bacterial meningitis.</li>
	<li>The prognosis for Naegleria infection is extremely poor, with a mortality rate above 95%.</li>
	<li>Diagnosis is typically made using a lumbar puncture or brain biopsy. 
	&nbsp;</li>
</ul>

[1] Naegleria fowleri — Primary Amebic Meningoencephalitis (PAM) — Amebic Encephalitis - Pathogen and environment. Centers for Disease Control and Prevention.

[2] Gharpure R, Bliton J, Goodman A, Ali IKM, Yoder J, Cope JR. Epidemiology and Clinical Characteristics of Primary Amebic Meningoencephalitis Caused by Naegleria fowleri: A Global Review. Clin Infect Dis. 2021;73(1):e19-e27. doi:10.1093/cid/ciaa520

[3] Parija SC. Naegleria infection and primary AMEBIC meningoencephalitis (PAM). Background, Pathophysiology, Epidemiology.

[4] Pervin N, Sundareshan V. Naegleria. [Updated 2022 Sep 19]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-.

[5] Ali M, Jamal SB, Farhat SM. Naegleria Fowleri in Pakistan. The Lancet Infectious Diseases. 2020;20(1):27-28. doi:10.1016/s1473-3099(19)30675-9.

[6] Mahmood K. Naegleria fowleri in Pakistan - an emerging catastrophe. J Coll Physicians Surg Pak. 2015;25(3):159-160.

[7] Tabassum S, Naeem A, Gill S, et al. Increasing cases of Naegleria fowleri during the time of COVID-19; an emerging concern of Pakistan. Int J Surg. 2022;105:106881. doi:10.1016/j.ijsu.2022.106881.

[8] Siddiqui R, Khan NA. Primary amoebic meningoencephalitis caused by Naegleria fowleri: an old enemy presenting new challenges. PLoS Negl Trop Dis. 2014;8(8):e3017. Published 2014 Aug 14. doi:10.1371/journal.pntd.0003017.

[9] Zeouk I, Sifaoui I, Rizo-Liendo A, et al. Exploring the Anti-Infective Value of Inuloxin A Isolated from Inula viscosa against the Brain-Eating Amoeba (Naegleria fowleri) by Activation of Programmed Cell Death. ACS Chemical Neuroscience. 2020;12(1):195-202. doi:10.1021/acschemneuro.0c00685.