What is Amoebic Meningitis?

Meningitis is a health condition that you may have heard of. It can be most common in younger people, including babies, children, adolescents and younger adults. However, anybody can develop the infection. It is an infection that targets the protective membranes that surround and protect the brain and spinal cord. These are called meninges, which is why the infection is called meningitis.

The World Health Organization report that meningitis is a highly fatal disease that can either lead to serious long-term complications in life or death. There are many different types of meningitis infection that a person can get, with each type having different routes of infection to the body.

Bacterial meningitis is the form of most concern to health officials, with a 1 in 10 death rate, and 1 in 5 people who recover from the disease having severe complications that can affect them for the rest of their lives. In this article, we will focus on one of the most severe forms of meningitis: amoebic meningitis. Unfortunately, almost all reports of amoebic meningitis result in death, with the mortality rate of the disease being higher than 90%.

What is amoebic meningitis?

In the UK amoebic meningitis is also called Primary Amoebic Meningoencephalitis (PAM) or Naegleriasis. It is a variation of meningitis that causes infection in the body from a type of bacteria called Amoebae. Amoebae are free-living organisms that are found in fresh water such as lakes and rivers.

The term ‘free-living’ means that the parasite does not need a host to survive (so it doesn’t need to live on a plant or an animal, it can survive on its own in the water).

The amoebae survive in water temperatures between 30°C and 45°C. This temperature of water is quite high so it is not likely that people in the UK would commonly be at risk of being exposed to these environments.

The suggested temperature for humans to swim in water is between 20°C to 30°C; which is slightly below the temperature that amoebae survive in, but it does present some risk when swimming in fresh waters of approximately 30°C. This is why swimming pools have chlorine in them; to keep the water clean and kill any potentially harmful bacteria.

The most common places that amoebae can be found are in ponds, lakes, rivers, hot springs, streams and unchlorinated swimming pools. These are the places where we are most likely to contract the disease because this is where our body would be in physical contact with the water.

What causes amoebic meningitis?

Amoebic meningitis can be caused if we ingest an amoeba organism. This could happen during fresh water swimming, diving, waterskiing, surfing, drinking water that has not been treated, and sitting in hot springs. Basically, any activity that involves fresh water of a warmer temperature.

No matter how healthy you are, if you ingest warm fresh water, there is a chance that this could be contaminated with amoeba organisms which presents a strong risk of you developing amoebic meningitis. Amoebic meningitis is the most deadly form of meningitis so can cause grave damage to all people due to its rapid rate of attacking the brain.

Due to the fact that the parasites survive best in warmer water, amoebic meningitis is more common in warmer climates (such as America and Asia), and during the warmer months of spring and summer. In the UK it is rare for fresh water temperature to reach the required temperatures, which makes developing the disease from fresh water swimming in the UK less likely.

Drinking warm, untreated water creates a high likelihood of amoebic meningitis developing here.

Unlike Legionnaires’ disease, which can be caused by drinking stagnant water from water dispensers that have not been cleaned, or have been dormant for long periods of time, amoebic meningitis cannot be caught by drinking water. However, you should still always ensure that to combat dehydration, you only drink clean water. Amoebic meningitis creates infection when it is ingested through the nasal passage; it cannot be caught by eating contaminated food.

Once the parasites enter the body, they invade the central nervous system and can cause permanent damage to the brain and nerves through blood poisoning (sepsis).

The most common way that you can become infected with the bacteria is after swimming or having your head submerged underwater that is unsanitary. However, infection can also occur from practices of flushing water up your nose to relieve sinuses.

Signs and symptoms of amoebic meningitis

The signs and symptoms of amoebic meningitis include:

• Sore throat.
• Headache.
• Confusion.
• Hallucinations.
• Reduced co-ordination – similar to symptoms of Ataxia.
• Nausea.
• Vomiting.
• High fever.
• Seizures.
• Reduced or changed taste and smell.
• Stiffness in the neck.
• Light sensitivity.
• Tiredness.
• Altered mental states.
• Behaviour changes.

A change in taste and smell is often the first symptom of amoebic meningitis that is reported by patients, and can take a week to develop following exposure. Following this, people develop headaches, a stiff neck, nausea, and light sensitivity. The symptoms of amoebic meningitis can progress rapidly and have been known to cause death within 10 days of infection.

How is amoebic meningitis diagnosed?

Amoebic meningitis can be diagnosed via a collection of examinations. A health professional will look at a person’s medical history and will carry out a physical examination and specific tests.

Some common tests that are used to diagnose meningitis are:

• Blood cultures – This is a blood sample that nurses take to assess if bacteria grow from the blood. The blood will also be studied under a microscope to check for bacteria in the blood.
• Scans – All hospitals use different types of scans to identify illnesses and diseases in the body. To help diagnose amoebic meningitis, professionals use CT scans and MRI scans to identify anything abnormal. When doing this, consultants can scan the head to look out for swelling in the area or inflammation. Scans of the chest can identify an infection that can be associated with meningitis. However, the scans cannot identify the key bacteria that cause meningitis, rather they rule out other illnesses.
• Lumbar puncture (spinal tap) – A spinal tap is a procedure that collects cerebrospinal fluid. This is the fluid that surrounds the brain and the spinal cord. It is this fluid that professionals need to test to determine the levels of key elements in the fluid. Professionals will look out for low sugar levels, an increased white blood cell count and an increase in proteins. This can also rule out other infections but may not always be able to find the amoebae.

Other techniques are available in specialised laboratories and are more likely to detect the amoebae. They include the following:

Taking a sample of blood from the patient and growing microorganisms in a laboratory until there are enough to identify the bacteria. Once the bacteria have been identified professionals can do a Polymerase Chain Reaction (PCR). This is a process to check for the genetic material of the amoeba. A PCR can also be completed following a biopsy of brain tissue.

Sadly, there are many cases of amoebic meningitis that do not get diagnosed properly until autopsy; meaning that the person has already died. The autopsy is the process to determine the cause of death.

How is amoebic meningitis treated?

Treatment for amoebic meningitis is treated as soon as is it suspected and diagnosed. This is because the amoebae are brain-eating organisms that can multiply which causes them to work faster. Due to this, the sooner that treatment of the illness starts, the higher the chance of the person surviving; and if they do survive, there is less risk of permanent brain damage.

Treatment for the illness is formed with a combination of different drugs including:

1. Conventional amphotericin B – This is an anti-fungal drug.

2. Rifampin – This is an antibiotic.

3. Fluconazole – This is another anti-fungal drug.

4. Miltefosine – This drug can cause birth defects in women. However, it is still a chosen drug to treat amoebic meningitis due to the high mortality rate of the illness. This means that the benefits of taking the drug outweigh the risks of not taking the drug, as without it a patient may die.

5. Azithromycin – This is a different antibiotic.

6. Steroid medication can also be prescribed to reduce swelling around the brain.

However, there is not one foolproof treatment plan for amoebic meningitis due to its rarity. As the illness has such a high rate of death, a combination of drugs is used so that if one drug doesn’t work, another drug may work alongside it.

Patients must ensure that they have plenty of fluids and medication that can reduce the fever and body aches. The clinical presentation of amoebic meningitis can appear similar to a regular bacterial meningitis; and missing this identification can lead to fatal consequences.

Patients are usually monitored with the illness in the intensive care unit. In the intensive care unit, practices such as hypothermia protocols can also be initiated, which the national library of medicine found to further support treatment.

How can amoebic meningitis be prevented?

There are some measures that can be taken to prevent amoebic meningitis from being caught.

These include:

• Do not dive, jump or swim in warm fresh water.
• Hold your nose if you need to jump into water, or wear protective equipment on your eyes and nose such as nose plugs to prevent exposure.
• Wading pools should be emptied and cleaned each day.
• Swimming pools and spas should be kept clean and maintained correctly.
• Keep sprinklers and hoses away from noses.
• When dealing with wet soil, do not touch your face until you have washed your hands.
• Keep your head above water when swimming in fresh water, hot springs, and other warm temperatures of water.
• When cleaning your nose via a syringe, ensure to use sterilised water.

Although amoebic meningitis is extremely rare, it is one of the most fatal forms of meningitis. Unfortunately, almost all people who develop the disease do not recover from it, or are left with life-lasting changes due to the damage that the parasite causes to the brain. The amoebae attack the brain, which could be described as eating the brain. This is why the damage caused cannot be reversed.

In the UK there are many different vaccinations that are available on the NHS, which are usually given to children to help prevent or offer protection against meningitis. You can find out if you have been vaccinated for meningitis at your local GP surgery.