Intro: Kerala is witnessing a surge in infections caused by Naegleria Fowleri, commonly referred to as the ‘brain-eating amoeba’, that thrives in water. So far, there have been 69 confirmed cases and 19 deaths. Preetu Nair speaks with Dr Rajeev Jayadevan, convenor (research cell), Kerala state IMA, to understand more about the deadly condition
Why are brain-eating amoeba (amoebic meningoencephalitis) cases on the rise in Kerala?
There are hundreds of thousands of brain infection (encephalitis) cases every year in India, causing a large number of deaths and disability. Although predominantly bacterial and viral in origin, the exact organism remains unknown in about 70% of cases. Amoeba is a relatively uncommon cause of encephalitis and requires additional tests for diagnosis. For this, the CSF (fluid from the spine) must be looked at under the microscope, using a wet mount preparation, by an experienced microbiologist who can accurately identify amoeba. This step is not routinely practised across the country.
However, in recent years, since Kerala has added this step among people with suspected brain infection, they are able to identify more cases involving amoebae. Those with early symptoms of brain infection such as headache, fever and vomiting must seek medical attention. If there’s a history of water entering the nose in the recent past, amoeba must be definitely suspected as a cause — regardless of where the person lives. Thus, this is not a real increase in incidence, rather a case of increased detection.
Why are most patients dying despite the detections?
This condition carries a very high global mortality rate of 97%. It’s partly because its difficult to diagnose, is diagnosed late or discovered after death on postmortem. In such case studies, the overall mortality will be high. In Kerala, where there is early diagnosis and treatment, the outcomes are better. A combination of drugs and expert care is essential for survival. Accordingly, the mortality in Kerala is far lower than what’s reported in worldwide literature.
Is nasal exposure to contaminated water the only cause or are there other causes too?
The easiest route for the amoeba to reach the brain is through the nose, which is much more than the two openings we see outside. The nose harbours a cavity with multiple connected passages and chambers located deep in the skull. A thin bone called the cribriform plate, which is about half the size of a fingernail, separates the brain from the nose cavity. Thus, along with contaminated water, if amoeba enters this cavity, it only has to burrow a short distance to enter the brain. Once it reaches the brain, it feeds on it and multiplies rapidly. The amoeba may also carry other organisms such as bacteria and fungi with it, which could potentially worsen the impact. One example is the recent case of a boy discharged alive from Trivandrum medical College following double infections (amoeba and fungus) in his brain. No other mechanisms of entry of amoeba into the brain have been scientifically proven, although there are various speculations.
What are the safety tips or precautions that need to be taken at the govt/individual level?
While it is helpful to maintain clean surroundings, chlorinate swimming pools and ensure safe drinking water, this will not put an end to amoebic brain infections. Amoebae are part of our environment. They are seen not only in rivers and ponds but also water pipes, drains, taps, water tanks and even shower heads. There are hundreds of species, of which only three or four cause brain infection. Amoebae can survive adverse conditions by temporarily switching to their cyst forms. Thus, they can’t be eliminated.
The most effective strategy, therefore, is to prevent amoeba from entering our nose. For that, people must stop washing their nose using water from the tap or the well, and also not allow water to enter their noses while swimming or bathing in natural water bodies. The nose is not designed to take water in, and if water gets in, some of it could get trapped in the chambers inside, allowing germs to enter the body and grow.
What is the situation in the rest of India? Are brain-eating amoeba cases limited to Kerala? If not, why is it only being detected here?
The earliest case of this condition was reported from West Bengal in 1971 by doctors who decided to look for amoebae as a potential cause of brain infection among children. In a series of 22 kids with brain infection, they found that two were due to amoebae. Both cases apparently survived. There are case reports from multiple other states as well. It is simple. If you test for it, you will find it.
Why are brain-eating amoeba (amoebic meningoencephalitis) cases on the rise in Kerala?
There are hundreds of thousands of brain infection (encephalitis) cases every year in India, causing a large number of deaths and disability. Although predominantly bacterial and viral in origin, the exact organism remains unknown in about 70% of cases. Amoeba is a relatively uncommon cause of encephalitis and requires additional tests for diagnosis. For this, the CSF (fluid from the spine) must be looked at under the microscope, using a wet mount preparation, by an experienced microbiologist who can accurately identify amoeba. This step is not routinely practised across the country.
However, in recent years, since Kerala has added this step among people with suspected brain infection, they are able to identify more cases involving amoebae. Those with early symptoms of brain infection such as headache, fever and vomiting must seek medical attention. If there’s a history of water entering the nose in the recent past, amoeba must be definitely suspected as a cause — regardless of where the person lives. Thus, this is not a real increase in incidence, rather a case of increased detection.
Why are most patients dying despite the detections?
This condition carries a very high global mortality rate of 97%. It’s partly because its difficult to diagnose, is diagnosed late or discovered after death on postmortem. In such case studies, the overall mortality will be high. In Kerala, where there is early diagnosis and treatment, the outcomes are better. A combination of drugs and expert care is essential for survival. Accordingly, the mortality in Kerala is far lower than what’s reported in worldwide literature.
Is nasal exposure to contaminated water the only cause or are there other causes too?
The easiest route for the amoeba to reach the brain is through the nose, which is much more than the two openings we see outside. The nose harbours a cavity with multiple connected passages and chambers located deep in the skull. A thin bone called the cribriform plate, which is about half the size of a fingernail, separates the brain from the nose cavity. Thus, along with contaminated water, if amoeba enters this cavity, it only has to burrow a short distance to enter the brain. Once it reaches the brain, it feeds on it and multiplies rapidly. The amoeba may also carry other organisms such as bacteria and fungi with it, which could potentially worsen the impact. One example is the recent case of a boy discharged alive from Trivandrum medical College following double infections (amoeba and fungus) in his brain. No other mechanisms of entry of amoeba into the brain have been scientifically proven, although there are various speculations.
What are the safety tips or precautions that need to be taken at the govt/individual level?
While it is helpful to maintain clean surroundings, chlorinate swimming pools and ensure safe drinking water, this will not put an end to amoebic brain infections. Amoebae are part of our environment. They are seen not only in rivers and ponds but also water pipes, drains, taps, water tanks and even shower heads. There are hundreds of species, of which only three or four cause brain infection. Amoebae can survive adverse conditions by temporarily switching to their cyst forms. Thus, they can’t be eliminated.
The most effective strategy, therefore, is to prevent amoeba from entering our nose. For that, people must stop washing their nose using water from the tap or the well, and also not allow water to enter their noses while swimming or bathing in natural water bodies. The nose is not designed to take water in, and if water gets in, some of it could get trapped in the chambers inside, allowing germs to enter the body and grow.
What is the situation in the rest of India? Are brain-eating amoeba cases limited to Kerala? If not, why is it only being detected here?
The earliest case of this condition was reported from West Bengal in 1971 by doctors who decided to look for amoebae as a potential cause of brain infection among children. In a series of 22 kids with brain infection, they found that two were due to amoebae. Both cases apparently survived. There are case reports from multiple other states as well. It is simple. If you test for it, you will find it.
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