Influenza Virons – Credit CDC PHIL
# 6443
We’ve a new study, conducted by the University of British Columbia, that finds a linkage between a past history of severe bouts of influenza and the likelihood of developing Parkinson’s disease later in life.
In fact, according to their research, a severe bout of influenza doubles a person’s chances of developing the neurological condition.
If all of this sounds vaguely familiar, it may be because we explored the idea of a Parkinson’s-Influenza link back in 2009 (see More On The Influenza-Parkinson’s Link).
Interestingly, the UBC researchers found that those who caught red measles as a child were 35% less likely to develop the disabling disease.
The article appears in the journal Movement Disorders, and the abstract may be read at:
Association of Parkinson's disease with infections and occupational exposure to possible vectors
M. Anne Harris PhD, Joseph K. Tsui MB, Stephen A. Marion MD, Hui Shen PhD, Kay Teschke PhD
While the study is behind a pay wall, we’ve a short press release from the University of British Columbia with some of the details. After which I will return with more.
Severe flu increases risk of Parkinson's: UBC research
Severe influenza doubles the odds that a person will develop Parkinson's disease later in life, according to University of British Columbia researchers.
However, the opposite is true for people who contracted a typical case of red measles as children – they are 35 per cent less likely to develop Parkinson's, a nervous system disorder marked by slowness of movement, shaking, stiffness, and in the later stages, loss of balance.
The findings by researchers at UBC's School of Population and Public Health and the Pacific Parkinson's Research Centre, published online this month in the journal Movement Disorders, are based on interviews with 403 Parkinson's patients and 405 healthy people in British Columbia, Canada.
Were this all the evidence – medical and occupational histories of a fewer than 1,000 people – then this might not be a terribly convincing study. But we’ve plenty of other research that suggest that some strains of influenza may be neurotropic - capable of infecting and damaging brain cells.
In 2009 a study appearing in PNAS found that the H5N1 virus was highly neurotropic in lab mice, and in the words of the authors `could initiate CNS disorders of protein aggregation including Parkinson's and Alzheimer's diseases’.
Highly pathogenic H5N1 influenza virus can enter the central nervous system and induce neuroinflammation and neurodegeneration
Haeman Jang, David Boltz, Katharine Sturm-Ramirez, Kennie R. Shepherd, Yun Jiao, Robert Webster and Richard J. Smeyne
Providing more analysis of this study, we’ve an article published on the St. Jude Children’s Research Hospital website, again from 2009.
Avian influenza strain primes brain for Parkinson’s disease
At least one strain of the H5N1 avian influenza virus leaves survivors at significantly increased risk for Parkinson’s disease and possibly other neurological problems later in life, according to new research from St. Jude Children’s Research Hospital.
<SNIP>
This avian flu strain does not directly cause Parkinson’s disease, but it does make you more susceptible,” said Richard Smeyne, Ph.D., associate member in St. Jude Developmental Neurobiology. Smeyne is the paper’s senior author.
“Around age 40, people start to get a decline in brain cells. Most people die before they lose enough neurons to get Parkinson’s. But we believe this H5N1 infection changes the curve. It makes the brain more sensitive to another hit, possibly involving other environmental toxins,” Smeyne explained.
Smeyne noted the work involved a single strain of the H5N1 flu virus, the A/Vietnam/1203/04 strain. The threat posed by other viruses, including the current H1N1 pandemic flu virus, is still being studied.
In 2011 a study by Boise State biology professor Troy Rohn appeared in PLOS ONE , which unexpectedly found immunohistochemical evidence of prior influenza A infection in the post-mortem brain tissues of 12 Parkinson’s patients they tested.
Immunolocalization of Influenza A Virus and Markers of Inflammation in the Human Parkinson's Disease Brain
Troy T. Rohn*, Lindsey W. Catlin
We’ve seen other (albeit largely anecdotal) evidence to support an influenza-neurological disorder link, and not just with Parkinson’s Disease.
During the 1918 pandemic, and the decade that followed, more than a million people around the world were afflicted by a mysterious neurological disorder called Encephalitis Lethargica (EL), which some researchers believe may have been precipitated by the influenza virus.
Other forms of neurological symptoms were also reported in the years (and decades) following the 1918 pandemic, leading some researchers to question whether or not it might be a part of some long-term sequelae of the virus.
Other scientists have linked EL with a post-streptococcal immune response, or believe it was an autoimmune response, and dismiss the link with the 1918 pandemic.
The cause remains a mystery.
Last year a study appeared in the Annals of Neurology, that suggests a link between contracting an upper respiratory infection and developing narcolepsy (cite Narcolepsy Onset is Seasonal and Increased Following the H1N1 Pandemic in China).
What these researchers found was, that in China, among a largely unvaccinated population, the incidence of Narcolepsy increased dramatically in the spring after the winter flu season.
This increase was most pronounced following the emergence of the H1N1 swine flu virus in 2009.
Those results are reminiscent of another study we saw in 2010 (see Lancet: The Influenza - Guillain Barré Syndrome Connection) that suggested the risks of developing GBS – another type of autoimmune disease - were far greater following a bout of the flu, than from receiving the flu vaccine.
While conclusive proof of a link between severe influenza A infection and the later development of neurological disorders has not yet been produced, the anecdotal evidence continues to mount.
All of which should provide additional motivation to get that seasonal flu shot every year, since the evidence suggests that it may be protecting you against something far worse than simply spending a miserable week in bed.
