Primary amoebic meningo-encephalitis: This rare brain infection caused the death of a Kerala teenager

The minister confirmed the boy’s demise and revealed that five similar cases of this rare infection had previously been reported in the state and, in all the cases, the patient died.

The first case was documented in 2016, followed by others in 2019, 2020, and 2022, the minister revealed.

“He was admitted with meningoencephalitis (brain fever) and to get confirmation, we have collected samples and sent it for testing,” an official from the District Medical Officer’s office told South First.

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What is primary amoebic meningoencephalitis?

Primary amoebic meningoencephalitis (PAM) is a rare and often fatal neurological disease caused by the Naegleria fowleri amoeba. Meningitis and encephalitis are types of brain fever caused by various infections, including viral herpes, TB meningitis, pneumococcal meningitis, and fungal meningitis.

Meninges are the protective layers of the brain. (Wikimedia Commons)

“One particular type of brain fever is caused by a protozoa infection affecting the brain’s protective coverings, known as the meninges. The term ‘meningo’ refers to the brain covering, while ‘encephalitis’ pertains to the brain,” said neurologist at Apollo Hospitals in Hyderabad, Dr Sudhir Kumar.

“In this case, the infective agent responsible is an amoeba and that is why it is called primary amoebic meningoencephalitis.”

He added that there are two types of amoeba — Acanthamoeba and Naegleria fowleri — that can cause this type of brain fever. Naegleria fowleri is more common and can be found in every country worldwide, including all states in India.

However, it is important to note that this infection is not highly prevalent. Typically, only one or two cases are reported per year in a given region.

“I have seen about a dozen cases in the past 25 years. A majority of cases had a history of taking bath in ponds or rivers,” said Dr Kumar told South First.

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How the amoeba enters the body

Naegleria fowleri is commonly found in warm freshwater environments, such as lakes, hot springs, and poorly-maintained swimming pools. The amoeba enters the body through the nose, and it then travels to the brain where it causes infection and inflammation.

“Another uncommon way of entry could be through a ritual, where people rinse their nostrils and nasal passages using water, including tap water,” said Dr Kumar.

Once inside the nasal passage, Naegleria fowleri travels through the olfactory nerve to the brain, where it causes severe damage to the tissues. The infection typically progresses rapidly, leading to inflammation of the brain and the meninges.

“It is crucial to understand that the primary entry point for this infective agent is the nose. Even in villages where people use normal ponds for bathing, the amoeba can enter through the nose and, subsequently, cause infection. The proximity of the nose to the brain allows the amoeba to enter and infect the brain, thus establishing its entry route,” explained Dr Kumar.

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Symptoms

In its early stages, symptoms of PAM are similar to symptoms of bacterial meningitis. Symptoms of PAM usually appear within a few days of exposure.

The initial symptoms include:

• Headache

• Fever

• Nausea

• Vomiting

Later symptoms include:

• Stiff neck

• Altered mental status (confusion)

• Lack of attention to people and surroundings

• Drowsiness

• Unconsciousness

• Seizures

• Hallucinations

• Coma

After the start of symptoms, the disease progresses rapidly and usually causes death within about five days (range 1 to 18 days).

It primarily affects healthy individuals, most commonly children and young adults who have been exposed to contaminated water during activities like swimming or diving. PAM is not transmissible.

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Diagnosis

Dr Kumar said that to diagnose encephalitis, initial investigations such as CTs and MRIs are conducted to obtain a clear understanding of the condition.

Lumbar puncture. (Wikimedia Commons)

However, to identify the specific causative agent, a lumbar puncture, also known as a spinal tap, is performed. This medical procedure involves inserting a needle into the spinal canal to collect cerebrospinal fluid for diagnostic testing.

The primary purpose of a lumbar puncture is to aid in the diagnosis of central nervous system diseases affecting the brain and spine.

“The collected cerebrospinal fluid is then sent to three different departments: Pathology, Biochemistry, and Microbiology. In the Microbiology department, experts examine the fluid under a microscope to identify any parasites present, thus confirming the specific causative agent of encephalitis,” said Dr Sudhir Kumar.

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Treatment

Unfortunately, the prognosis for PAM is extremely poor, with a high fatality rate. The infection progresses rapidly and, if left untreated, it can lead to death within a matter of days.

Immediate medical attention is crucial in increasing the chances of survival. Treatment options include aggressive use of antifungal and antimicrobial drugs, as well as measures to reduce brain swelling and inflammation.

“Unfortunately, the mortality rate for encephalitis is quite high, with approximately 70-80 percent of affected individuals succumbing to the infection. It is important to note that survival does not necessarily depend solely on the administration of medicines,” said Dr Kumar.

“In cases where the infection is mild, the person’s own antibodies and immune system play a crucial role in fighting off the infection. The immune response helps in combating the causative agent and preventing the infection from progressing further,” he added.

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Preventing primary amoebic meningoencephalitis involves avoiding activities in warm freshwater bodies where the amoeba is present, especially in areas with stagnant or poorly-maintained water. Taking precautions such as using nose clips or holding your nose shut when participating in water-related activities can also help minimise the risk of infection.

“When performing the jala neti ritual, it is essential to use only distilled or sterilised water. Boiling the water can also effectively kill the amoebae responsible for these infections.

“However, it is important to note that chlorination of water may not completely eliminate these amoebae, as they have shown resistance to chlorination methods.

“Therefore, it is advisable to refrain from using water directly from the tap for these purposes, as it may not be adequately sterilised to prevent the risk of infection,” explained Dr Kumar.