The role of fungi in the etiology of multiple sclerosis.
Benito-León J, Laurence M.
Front Neurol 2017; 8:535.
Multiple sclerosis (MS) is a chronic inflammatory disorder of the central nervous system. Infectious triggers of MS are being actively investigated. Substantial evidence supports the involvement of the Epstein-Barr virus (EBV), though other viruses, bacteria, protists, and fungi are also being considered.
Many links between fungi and diseases involving chronic inflammation have been found recently. Evidence linking MS and fungi is reviewed here. The HLA-DRB1*15 allele group is the most important genetic risk factor of MS, and is a risk factor in several other conditions linked to fungal infections. Many biomarkers of MS are consistent with fungal infections, such as IL-17, chitotriosidase, and antibodies against fungi. Dimethyl fumarate (DMF), first used as an industrial fungicide, was recently repurposed to reduce MS symptoms. Its mechanisms of action in MS have not been firmly established. The low risk of MS during childhood and its moderate association with herpes simplex virus type 2 suggest genital exposure to microbes (including fungi) should be investigated as a possible trigger. Molecular and epidemiological evidence support a role for infections such as EBV in MS.
Though fungal infections have not been widely studied in MS, many lines of evidence are consistent with a fungal etiology. Future microbiome and serological studies should consider fungi as a possible risk factor for MS, and future clinical studies should consider the effect of fungicides other than DMF on MS symptoms.
One may be forgiven for thinking that neurology is all about neuroinflammatory and neurodegenerative diseases. This is because these disorders seem to get a lot of attention. But nothing could be further from the truth-globally, infections impose a heavier burden on neurological practice than say Multiple Sclerosis (MS) or Parkinson’s disease (PD). And medical advances have done very little to deter all sorts of creatures from invading the nervous system.
The major types of organisms that infect the nervous system are viruses and bacteria, but fungi and parasites also take their toll. In this blog we will focus on the 7 most devastating viral neurological infections.
Encephalitis is infection of the brain substance, as opposed to meningitis which is infection of the covering of the brain. Viral encephalitis, for some reason, tends to favour the temporal lobes of the brain causing seizures and memory problems, amongst other symptoms. The main villain responsible for viral encephalitis is herpes simplex type 1 (HSV1), but almost every other virus can carry out the job with deadly precision. The list is long and includes geographically specific viruses as West Nile and Japanese B. Check out the full list of causesof viral encephalitis and its management.
Hepatitis E virus is just emerging as a scourge of neurology. It is particularly villainous because of its protean manifestations, from Guillain Barre syndrome (GBS) to neuralgic amyotrophy (brachial neuritis), from transverse myelitis to idiopathic intracranial hypertension (IIH). Check out thefull neurological manifestations of HEV.
Influenza is bad, and H1N1 is a particularly nasty variant. This subtype of Influenza A is epidemic in pigs and birds, and unleashes havoc when it crosses over to humans. Its nervous system manifestations include encephalopathy, Guillain Barre syndrome (GBS), acute demyelinating encephalomyelopathy (ADEM), and stroke. Not one to be treated lightly at all. Check out everythingabout Influenza H1N1 and the different ways influenzaaffects the nervous system.
This new kid on the infection block is fast establishing itself as a menace. Apart from causing myelitis, meningoencephalitis, encephalitis, encephalomyelitis, Guillain-Barre syndrome (GBS), and myasthenia gravis (MG), it is responsible for a variety of congenital defects, particularly microcephaly. Zika virus pathology and management are extensively covered in neurochecklists. Or check out 20things we now know for certain about the Zika virusonour sister blog, The Neurology Lounge.
This ancient virus gained recent notoriety when it ravaged a large section of West Africa, sending chilling waves across the world. It is an RNA filovirus whose main reservoir is bats. It causes, among other things, an encephalitis and meningoencephalitis. It appears to be on vacation in the meantme, but it will surely rear its ugly head sometime soon. Check out the comprehensive clinical features and management of Ebola virus disease on neurochecklists.
The varicella virus must take the prize for the most diverse ways a virus affects the nervous system. Neurochecklists has listed >20 neurological manifestations of VZV, ranging from herpes zoster to post herpetic neuralgia (PHN), from meningitis to encephalitis. VZV also causes all forms of cranial and peripheral neropathy, and may result in stroke, aneurysms, and giant cell arteritis (GCA). Not to mention the curiously named progressive outer retinal necrosis (just don’t mention its acronym!). Check out thefull VZV on neurochecklists.
Check out the other deadly viral neurological infections on neurochecklists: