Demics: Serious Swine Flu Post

The swine flu is an "emerging infectious disease." An emerging infectious disease is a disease caused by a micro-organism such as bacteria or virus that has recently appeared.[1] This classification for swine flu is obvious and without controversy unless you are a germ theory denialist.

Where things get hazier is when we begin to look at the various "demic" terms that can be applied to swine flu. The one we are hearing most is "pandemic." Swine flu is called a pandemic not because of its severity, total number of cases, or body count but because of how widespread it is. There are less than 1,000 confirmed cases so far, but swine flu has been report on 4 continents plus New Zealand with the majority of cases in North America (Mexico and the United States).

You may have noticed we haven’t heard the swine flu called an epidemic very much. An epidemic is when there are lots of cases of the disease in a population. So far we don’t have lots of cases in any given population. But it is possible we might be talking about a swine flu epidemic in Mexico if cases there continue to increase. The key thing to recognize is that pandemic is not the plural of epidemic. We can and do have a pandemic without any epidemics.

A final "demic" term to mention is "endemic." A disease is endemic in a given population if it is always present but at low levels. Regular flu is endemic in the United States. Measles was endemic before the vaccines in the industrialized world and is still endemic in regions whose population isn’t well vaccinated.

Looking forward the educated guess (using good math and the best available infection statistics) is that the swine flu will play out with a severity in the US similar to an extra flu season. You are correct to be relieved to hear that. But also recognize that in an average year 30-50,000 Americans die from the flu. So while there is no need to panic there is a reason public health officials are treating this as something serious.

PS. The BBC series Surviors is worth watching for good drama but it is not a guide for what to expect.

[1] Emerging infectious disease can also be applied to infectious diseases that are previously known but are suddenly infecting more people or infecting a people in a much larger geographic area than before.