Brain-eating amoebas kill by turning your body against you - health - 13 May 2015 - New ScientistThere was me thinking the 'Intelligent Designer' couldn't get any nastier when I wrote a couple of months ago about the parasitoid wasp that turns a ladybird into a zombie by injecting it with a mind-controlling virus. Now I've come across something else which surely competes with this for sheer malevolent nastiness. Of course, sheer incompetence could also explain it.
It's an amoeba which destroys the human brain, but it doesn't do it simply by eating it - that would be too simple for our malevolent 'Intelligent Designer'. It does it by making us destroy our own brain, not just because our immune system isnt fit for purpose but also because of the way our brain is fitted into our skull.
Naegleria fowleri is a species of amoeba which lives in warm, freshwater pools, normally living on a diet of local bacteria. However, should someone take a dip in one of these pools and gets water up their nose, some of the amoebas might penetrate the mucous membrane and find their way up the nerves to the brain, where they start eating brain cells.
Thankfully, this is a reasonably rare event but it is almost always fatal. Of 132 people in the USA known to have been infected since 1962, only three survived. Infection is more common elsewhere: in Pakistan some 20 people a year die from infection by N. fowleri. But the amoeba itself is almost certainly not what actually kills people. According to a paper published in Acta Tropica by Abdul Mannan Baig from Aga Khan University in Karachi, Pakistan, the main culprit could be the host's immune system itself which does most of the damage.
The immune system's response is to flood the brain with immune cells. Not only do the enzymes released by the immune cells damage the brain cells themselves, but this response causes inflammation and swelling. Normally, swelling and inflammation around an infection site are exactly what's needed because this brings more blood and more lymph to the area, helping to fight the infection and promote healing. In the brain, however, this response can be disastrous.
The problem is another piece of crap design. The brain is contained in a boney case which can't expand and from which there is only one significant outlet through which pressure build-up can be dissipated - the foramen magnum, i.e., the hole that the brain stem passes through to form the spinal cord. Basically, when the brain swells, it's like trying to squeeze toothpaste out of the nozzle. The result is compression of the brain stem by a process the medical profession know as 'coning'. And this is where the second piece of crap design comes in.
All the deep centres needed to maintain basic life-support such as respiration, blood pressure and heart rate are located in the brainstem and get knocked out by coning.
Abdul Mannan Baig, of the Department of Biological and Biomedical Sciences at Karachi University, believes he has shown that brain cells actually survive longer without an immune response anyway, so he recommends a treatment for amoebic encephalitis which amounts to over-riding the 'Intelligent Design' of the body and suppressing the body's immune system before hitting the parasites with specific drugs. This should help reduce the risks from brain-swelling to.
Abstract
Pathogenic free living amoeba like Naegleria fowleri, Acanthamoeba spp., and Balamuthia mandrillaris are known to cause fatal “amoebic meningoencephalitis” (AME) by acquiring different route of entries to the brain. The host immune response to these protist pathogens differs from each another [sic], as evidenced by the postmortem gross and microscopic findings from the brains of the affected patients. Cited with the expression of ‘brain eating amoeba’ when the infection is caused by Naegleria fowleri, this expression is making its way into parasitology journals and books. The impression that it imparts is, as if the brain damage is substantially due to the enzymes and toxins produced by this amoeba.
A detailed review of the literature, analysis of archived specimens and with our experimental assays, here we establish that with Naegleria fowleri, Acanthamoeba and Balamuthia spp., the infections result in an extensive brain damage that in fact is substantially caused by the host immune response rather than the amoebas. Due to the comparatively larger sizes of these pathogens and the prior exposure of the amoebal antigen to the human body, the host immune system launches an amplified response that not only breaches the blood brain barrier (BBB), but also becomes the major cause of brain damage in AME. It is our understanding that for Naegleria fowleri the host immune response is dominated by acute inflammatory cytokines and that, in cases of Acanthamoeba and Balamuthia spp., it is the type IV hypersensitivity reaction that fundamentally not only contributes to disruption and leakiness of the BBB, but also causes the neuronal damage. The further intensification of brain damage as expected does comes from the toxins and enzymes secreted by the amoeba, which causes the irreversible brain damage, a phenomenon, which could very well continue even after the death of the patient.
So, to the acute embarrassment of creationists (or it would be if they knew about it and understood it), medical science is recommending switching off one badly designed system to reduce the risks coming from another example of crap design in the human body, all to overcome the harm being done by a nasty little parasite that, if we believe creationists, was also designed by their magic friend and, apparently, with the omniscient intention of causing this problem in the first place.
As Earth heats up, the habitats for these parasites will become more common further north. A case of amoebic encephalitis has already been reported from the US state of Minnesota and probably one case of infection from drinking water - courtesy of the 'Intelligent Designer', apparently.
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