According to the feature, pandemic is the sixth most frequently looked-up word at Merriam-Webster's online dictionary this year. It is defined there as "occuring over a wide geographic area and affecting an exceptionally high proportion of the population".
Is it the same with an epidemic? It is not. It seems an epidemic is determined by a certain percentage of deaths above what is considered normal for a period. That percentage is called the "epidemic threshold".
On the other hand, a pandemic is characterized by a new strain that has not infected people before, it is on a global scale, and it is unusually deadly. Apparently, this is now a very real possibility with swine flu.
The World Health Organization (WHO) has developed a system of identifying where we stand with regards to pandemic flu. The system has six phases:
- Phase 1 -- No new influenza virus has been found in people or animals.
- Phase 2 -- New virus has appeared in animals, but no human cases.
- Phase 3 -- A new strain of animal influenza virus infects humans, but there have not been human-to-human infections.
- Phase 4 -- The new virus passes from person to person, but transmission is limited and confined to a certain location.
- Phase 5 -- There is frequent transmission of the virus between people in a particular place, but it hasn't spread to the rest of the world.
- Phase 6 -- Pandemic. The virus is widespread worldwide.
As of this posting, it has been reported that we are now at Phase 4.