Influenza pandemic

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In 1918, an influenza pandemic christened the Spanish Flu caused the death of over 40 million people worldwide. With mortality statistics reaching millions for other subsequent pandemics, the phenomenon is one to be feared.

Influenza is a virus affecting the respiratory system and there are three types. Type A is the cause of most epidemics and pandemics and affects birds, humans and mammals. It is the cause of the bird flu causing such concern recently and is considered a likely source of the next pandemic. Types B and C are considered less threatening and the latter type in particular has not been responsible for any serious influenza pandemics.

If the virus is limited to a local area only, it is considered an outbreak. If it affects a wider area, perhaps on a national level, it is termed an epidemic and if it reaches global proportions, it becomes a pandemic.

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Stages of a pandemic

The World Health Organization has classified pandemics to six levels:

  • Phase 1: this is low risk, where no new virus subtypes have surfaced.
  • Phase 2: a new virus subtype has appeared in animals, and though they can cause illness in people, there are no new subtypes in people themselves.
  • Phase 3: in the self-limiting phase, a new subtype has appeared within humans but there are only rare instances of human-to-human infection.
  • Phase 4: there is localized human-to-human infection.
  • Phase 5: an epidemic breaks out when human-to-human transmission starts occurring on a larger scale.
  • Phase 6: in a full-blown pandemic, there sustained global transmission.
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Prevention

With the threat of a new influenza pandemic in bird flu, more properly called avian influenza, the increasing number of cases in increasing numbers of countries is a cause of great concern. Vaccines are unlikely at the beginning of an outbreak as they must be tailored to the specific strain of virus causing the problem and this may take months to develop. Anti-viral drugs again are only effective against certain strains and, should the virus mutate, they then become resistant to the drug.

Personal habits such as frequent hand-washing, wearing masks and sneezing into one’s hand or crook of the arm are likely to be just as effective as drugs which are one generation behind a rapidly changing virus. Avoiding crowded areas such as the workplace or school is also advisable.

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