One of the reasons that the flu spreads like wildfire each year is that there are many influenza types. Even though it is a viral infection that people can build immunity to, it is able to change from year to year, making it difficult for people to build up enough immunity to the virus. This is also why health care professionals often wait until they know which influenza types are most common each year before releasing a vaccine to ensure protection for the most people possible.
There are three main influenza types, which are broken down into many sub strains that have the potential to spread each year. These are:
- Influenza Type A - the most common of the influenza types, Type A has the highest potential for infection because it can be found in people and many animals, with birds being the main carrier. Subtypes depend on mutations in two proteins found on the virus, hemagglutinin (HA) and neuraminidase (NA). There are 15 known HA types and 9 known NA types, with many combinations of the two. The most common are:
- N1H1 (also known as Spanish Flu or Swine Flu)
- H2N2 (Asian Flu)
- H3N2 (Hong Kong Flu)
- H6N1 (Bird Flu)
- Influenza Type B - this type of influenza is less common, as it is only found in humans, seals, and ferrets. This form is less genetically diverse, which allows people to build stronger immunity towards it.
- Influenza Type C - The least common of the influenza types, this form infects humans, dogs, and pigs. It rarely spreads very far, and is usually mild and restricted to local outbreaks.
The way that health care providers treat the flu each year depends on what type they are dealing with. In the case of severe outbreaks, such as the Spanish Flu outbreak in the early 1900s and the recent Swine Flu pandemic, vaccinations and quarantines may be required to avoid worsening and spreading of the illness.
If you suspect you or a family member is suffering form the flu, try your best to avoid any unecessary contact and consult with your primary care provider for more influenza information in order to prevent the spread of the virus and avoid any complications.