Amoebic Meningoencephalitis: Who Gets Infected?

What is Amoebic Meningoencephalitis?

Amoebic meningoencephalitis often referred to as Primary Amoebic Meningoencephalitis (PAM)is a medical condition affecting the brain and is characterized by the inflammation of the brain followed by a destruction of the brain and the linings of the brain.

Though there are numerous species of Naegleria, not all of them are deadly. Naegleria is commonly found in fresh water lakes, ponds, hot springs, and rivers. Amoebic meningoencephalitis that is caused by Naegleria fowleri can be fatal. People typically get infected by Naegleria fowleri when contaminated water enters their body through their nose. This can happen when people are swimming or diving in warm fresh water lakes or ponds. 

Naegleria fowleri and the earliest cases of amoebic meningoencephalitis were reported in the 1960s in Australia. Since then, numerous countries have reported instances of amoebic meningoencephalitis caused by Naegleria fowleri. The most common victims of amoebic meningoencephalitis are children who are unaware of the dangers associated with swimming in fresh, unclean water.

Who gets infected by Amoebic meningoencephalitis?

The ideal thriving conditions for Naegleria fowleri are presence of water and temperatures ranging between 28 to 50ºC. Warm, fresh water bodies including lakes, rivers, geothermal water in the form of hot springs, and warm water discharge from industrial plants are some of the places where Naegleria fowleri can thrive.

 It is important to note that Naegleria fowleri cannot thrive in any water body that has more than two percent salt. Examples of such water bodies include river estuaries and sea water.

Amoebic meningoencephalitis happens when water infected with Naegleria fowleri enters the nose when a person indulges in water-related activities. After entering the nose, the amoeba travels up to the brain and the central nervous system and causes the primary amoebic meningoencephalitis. Naegleria fowleri travels up to the brain through the olfactory nerve.

PAM is a rare disease but in most of the cases, it is fatal. It must be noted that PAM is not caused by drinking infected water. It is also important to note that there has never been any report of spread of infection from one person to the other. Even in cases involving transplantation of organs from donors who are infected with Naegleria fowleri, the recipients has never been infected. However, recent studies have also shown the presence of Naegleria fowleri outside the brain. Therefore, the risks associated while transplanting organs from Naegleria fowleri infected people cannot be totally overruled.

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The first reported occurrence of amoebic meningoencephalitis in the US was in 1962 in Florida. Infections have also been reported in the Southern-tier states of the US and most cases of amoebic meningoencephalitis have been caused by swimming in warm freshwater rivers and lakes. Most cases of amoebic meningoencephalitis have been reported in children less than 18 years of age.

The risk of infection from Naegleria fowleri is the highest during the months of July and August when water levels are low and water temperatures are at the maximum.

Symptoms Of Amoebic Meningoencephalitis

The symptoms of amoebic meningoencephalitis are quite similar to bacterial meningitis. The symptoms of amoebic meningoencephalitis are observed about 5-7 days after exposure to Naegleria fowleri. Most people die within 1-12 days after the symptoms of amoebic meningoencephalitis begin to appear. PAM is extremely difficult to detect as the infection spreads very rapidly and in most cases, the diagnosis is made after the death of the patient. Death is almost certain in all the cases of amoebic meningoencephalitis. 

There are two stages of symptoms exhibited by people suffering from amoebic meningoencephalitis. These are listed below:

• Stage 1: The stage 1 of amoebic meningoencephalitis is characterized by severe and persistent frontal headache, nausea, fever, sleepiness, and vomiting.

• Stage 2: The stage 2 of amoebic meningoencephalitis is characterized by a stiffness of neck, seizures, hallucinations, altered mental alertness, and coma.

Risk factors for Amoebic Meningoencephalitis

Although amoebic meningoencephalitis is a fatal disease, the chances of its occurrence are extremely rare. In the past 10 years, only 32 cases of amoebic meningoencephalitis have been reported in the United States. These figures explain the rarity of its occurrence despite the fact that there are millions of exposures to recreational waters.

People who indulge in recreational water activities should be aware of a certain level of risk associated with exposure to Naegleria fowleri. However, it is important to note that the occurrence of Naegleria fowleri is quite common but chances of infection are extremely rare. The number of cases of amoebic meningoencephalitis is quite low even though there are millions of people who use the same or similar water throughout the United States.

Diagnosis and Treatment of Amoebic Meningoencephalitis

Amoebic meningoencephalitis is typically diagnosed by performing specific laboratory tests. Laboratory tests are performed to detect the presence of Naegleria fowleri organisms, Naegleria fowleri nucleic acid, and Naegleria fowleri antigens in the cerebrospinal fluid, tissue specimens, and biopsy. Some test methods adopted for examining the presence of Naegleria fowleri include direct visualization, polymerase chain reaction, immune-histochemistry, and amoeba culture.

Till date, only two cases of survival have been reported for amoebic meningoencephalitis in the US. The medications administered to these patients included Amphotericin B, Rifampicin, Dexamethasone, Ceftriaxone, and Phenytoin. Miltefosine has also been found to be effective in killing Naegleria fowleri in the laboratory.

Read More: Brain-Eating Amoeba Due To Stagnant Water, CDC Says

Certain steps that can be taken to lower the risk of infection from Naegleria fowleri are listed below:

• Try to avoid lowering your head under water when indulging in water activities in hot springs and other untreated water bodies.

• Use nose clips and keep your head above water when swimming in warm fresh waters.

• For rinsing your sinuses and for nasal rinsing and ablution rituals, always use chlorine bleach.