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Pandemic flu" has been one of the buzzwords of late 2005. But how does the phrase that's on everyone's lips differ from "epidemic," that other well-worn disease term?
Apparently, a lot of people aren't sure. Merriam-Webster reports that "pandemic" is the seventh most frequently looked-up word in its online dictionary this year. The definition: "occurring over a wide geographic area and affecting an exceptionally high proportion of the population."
This is almost the same as the dictionary definition for "epidemic," and it doesn't explain much when it comes to influenza -- a.k.a. the flu.
An epidemic of influenza is different from the dreaded pandemic that scientists and world health officials fear is nigh. We might see an epidemic of seasonal influenza during any given year. In fact, we just had one.
Flu reached epidemic levels in the U.S. for 10 weeks in a row during the 2004-2005 season. Records kept by the CDC show that during the week ending March 5, 2005, 8.9% of all deaths reported in 122 U.S. cities were due to influenza and pneumonia (a common complication of the flu).
The CDC's definition of a flu epidemic relates to the percentage of deaths in a given week caused by influenza and pneumonia. The "epidemic threshold" is a certain percentage above what is considered normal for that period. The normal level, or baseline, is statistically determined based on data from past flu seasons.
Christine Pearson, a spokeswoman for the CDC, cautions that the definition of an influenza epidemic doesn't apply to other diseases.
Seasonal flu epidemics may sicken millions, but those who die are typically a small number of the elderly, very young children, and people with weak immune systems. That's not the case during the worst influenza pandemics.
There are two main features of an influenza pandemic. First, the virus is a new strain that has never infected people before. Second, it's on a global scale. Sometimes it's also unusually deadly.
Step-by-step explanation: