Tuesday, April 28, 2009

Pandemic vs. Epidemic

What is a pandemic? How is it different from epidemic? With all the news about a possible swine flu pandemic, I am sure all of you want to know. Martin F. Downs of WebMD explains.

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.

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