Influenza - Atchoum! But is it a cold or the flu?

Dr. Talbot and his teamZoomZoom
© Robert Alain, SME, INRS-Institut Armand-Frappier and Joanna Prime

Article published in the Courrier Laval, on October 29, 2006.

It’s that time of year again, when headaches and sniffles get the best of us. The contagious season of colds and the flu is back. Since SARS and the mention of an eventual pandemic of avian flu, these diseases have become worrisome. But what do we really know?

According to Canada’s Public Health Agency, the flu kills between 4,000 to 8,000 Canadians each year. The Influenza viruses are responsible for these deaths. There are three types. The B type Influenza viruses provoke localized epidemics. The type A viruses are responsible for pandemics, i.e., epidemics on a planetary scale. Type C defines benign viruses. If we look more closely, we notice that these Influenza viruses possess eight DNA sections, H and N, for example. All these segments can undergo mutations, mix together, and create a multitude of different viruses such as the avian flu virus (or H5N1). These changes fool our immune system, which allows the virus to attack us each year. This is why vaccination is renewed every year.

The flu was also responsible for many deaths in the last century. The Spanish influenza in 1918 killed nearly 30 million people; the Asian flu in 1957, 4 million; and the Hong Kong flu in 1968, 2 million. According to Health Canada, "Canadian families should take simple measures immediately to be able to react more appropriately in case of an influenza pandemic". This is because the chronicity of these influenza pandemics indicates that we should fear a new one without, however, being able to predict when. The last ones having all originated in south-east Asia, it is suspected that the new source of infection will come from this region; wild birds ensure its propagation during their migrations.

The last pandemic, SARS or Severe Acute Respiratory Syndrome, allowed public opinion to be sensitized to the behavior that should be adopted under such circumstances. This disease is caused by the coronavirus, a family of viruses responsible for a third of all colds. "People are now aware of the mode of propagation of these viruses and how to protect against them" says Pierre Talbot, a researcher on the coronavirus at the INRS-Institut Armand Frappier. When they are sick, some people wear masks when using public transportation and when visiting hospitals. Although coronaviruses are much more stable than Influenza viruses, this does not mean that they are benign. "Patients afflicted with multiple sclerosis have T lymphocytes that recognize both the coronavirus and the myelin proteins." This phenomenon is due to the structural similarity of proteins between these two elements. The coronavirus, present in the human brain, could be the trigger element for neurological diseases in predisposed people.

There is no vaccine against the common cold but this year’s vaccine against influenza will be available starting on November 1, soon enough to protect against the flu peak that occurs in mid-December or later.