Flu in the News

Dr Duncan Shrewsbury II  NOV 25 2016

 
Every year, we hear something that is at least a little scary in the news regarding influenza. In 2008 bird ‘flu hit the headlines, then in 2010 it was ‘Swine’. Recent headlines have raised concern of the re-emergence of ‘Bird flu’ with reports of outbreaks in the Middle East and Europe. Sensationalism aside, what does this actually mean in real terms?

What is the ‘flu?

‘Flu, or influenza, is the term given to an illness affecting the respiratory tract (nose and mouth, throat, and lungs) which can be caused by viruses from any one of 3 ‘influenza families’ (types A, B and C). These viruses can also affect animals too (bird ‘flu primarily affecting birds, and swine ‘flu primarily affecting pigs).

There are hundreds, if not thousands, of different mutations of the viruses within each family. These mutations are roughly characterised according to the ‘drift’ and ‘shift’ (changes) in the sticky proteins (dubbed ‘H’ and ‘N’) that coat the virus particles. It is these sticky proteins that allow these viruses to attach to the cells that line our nose and throats and cause infection, characterised by: sore throat, runny nose, headache, fever, cough, and generalised muscle aches.

The bird ‘flu virus that caused the pandemic in 2008-9 was of the Type A family, and had the sticky proteins H5 and N1, so it is dubbed A-H5N1.  The utility of these proteins , coupled with rapid evolution of the virus, allowed it to cross species barriers.

Every year, as the weather changes, and people come closer together, these viruses are spread through droplets (e.g. particles of mucous [snot]) from one person to another, and eventually cause ‘pandemics’ (where an infection spreads through a wide community, across several countries.) In our global society, planes become vectors and airports reserviors.

How does our immune system respond?

Our body’s immune system (some of the white blood cells, and antibodies) are responsible for tackling viral infections. After an initial infection with one virus, the immune system gets better, and faster, at recognising the virus based on these sticky bits (e.g. having had H5N1 before, your body will have antibodies against H5N1 sticky proteins, and cells that will quickly recognise H5N1 as something nasty that needs destroying). This will result in the virus being blocked and destroyed before it can cause the full infection.

We can try to ‘educate’ the immune system with a vaccine. These are usually in the form of an injectable vaccine, made up of bits of ‘killed’ virus (totally unable to invade cells), or a nasal vaccine of virus particles that have been ‘attenuated’ (damaged so they cannot cause infection). These vaccines are made twice a year, based on predictions of which viruses (the constant mutations causing a new ‘strain’) are likely to spread and cause infection around the world.

Sometimes these predictions are very accurate, and sometimes they are not, but even when scientists predict the wrong strain, vaccines often confer some ‘cross-reactivity’ (e.g. vaccination against one virus, such as A-H5N1, will prime the immune system enough to give some protection against another influenza virus, like A-H1N1.)

When to worry

For many people, who are otherwise fit and well, an infection with a ‘flu’ virus can be a rough few days in bed with a temperature and sore head. For others, it can be potentially life threatening, requiring admission to hospital. Anything that potentially weakens your immune system (e.g. some medicines, like steroids or cancer treatments), age (the immune system of babies and the elderly aren’t very quick to respond to these infections), and other illnesses (e.g. asthma or other lung diseases) can affect your body’s ability to fight this infection, and can increase your risk of severe illness.

Is there a treatment?

There are some medications that can block the ability of a virus to replicate, and therefore cause ongoing infection in a body. Such ‘antivirals’ like Tamiflu (oseltamivir) are suggested for use in cases of suspected ‘flu in some people (e.g. pregnant women, or others who may be vulnerable). However, there is very little evidence that these medications are effective, with an estimated benefit of shortening symptoms by about 12 hours. Pharmaceutical companies often like to oversell minimal benefit for maximal profit.

Prevention is more effective than cure. Simple measures, like those promoted by the ‘catch it, bin it, kill it’ campaign (cough or sneeze into a tissue, throw that in the bin, and then wash your hands), and maintaining overall good health will help [7]. If you are eligible (check the NHS Choices website) for the ‘flu vaccine, book in with your GP nurse and get it early.

This will not only protect you to a certain extent, but also – by blocking the ability for a virus to infect you, you prevent yourself from becoming a ‘reservoir’ for that virus, and then do not spread it. Thus, you are also helping to protect those around you (this is called ‘herd immunity’).

Any opinions above are the author's alone and may not represent those of the NHS or  Mind and Medicine. Any comment is based on the best available evidence at the time of writing.  All data is based on externally validated studies unless expressed otherwise. Novel data is representative of sample surveyed. Online recommendation is no substitute for seeing your own doctor and should not be taken as medical advice.

Sources

1). Graham K (2016) H5N8 bird flu – Iran and Denmark report outbreaks. Digital Journal: http://www.digitaljournal.com/tech-and-science/science/h5n8-bird-flu-spreads-iran-and-denmark-report-outbreaks/article/480096

2). Centre for Disease Control: Key Facts about Influenza: http://www.cdc.gov/flu/keyfacts.htm

3). World Health Organisation: Seasonal Influenza Factsheet: http://www.who.int/mediacentre/factsheets/fs211/en/

4). Centre for Disease Control: Key Facts about Influenza Vaccination: http://www.cdc.gov/flu/protect/keyfacts.htm

5). World Health Organisation. Weekly empidemiological record: vaccines against influenza WHO position paper- November 2012: http://www.who.int/wer/2012/wer8747.pdf

6). National Institute of Health and Care Excellence. (2015) Clinical Knowledge Summary: Treating influenza: https://cks.nice.org.uk/influenza-seasonal#!scenario 7). https://www.gov.uk/government/news/catch-it-bin-it-kill-it-campaign-to-help-reduce-flu-infections