In reply to: http://www.straightdope.com/classics/a4_104.html
It seems that in this discussion something obvious was left out and I’m wondering why. Birds migrate in winter-time.
But people, before you make a run for your shotguns and do Mao Ze Dong’s mistakes all over I would break a lance for the flu. I think of flu as the breath of Evolution. (For the Bible-belt I would add: as God planned it.) Without change Life would come to a grinding halt.
Here’s my theory. Ever get a runny nose after being out in freezing weather, even though you’re feeling perfectly healthy? Well all that mucous floating around when you go back inside (inside work areas, classrooms, etc.) may very facilitate the spread of those viruses which are already extant in the population. That doesn’t happen in the summer (and yes schools are good “melting pots” for all sorts of germs, but in summer well you know).
That doesn’t happen in Florida at anytime of the year, but they still have cold/flu season in the winter.
It’s those damn tourists, bringing their northern snot with them.
Think how many doorknobs you touch in winter as compared to summer. For every doorknob you touch, think about how many people have touched that same doorknob.
The fact is that you are just in contact with more people both by being in the same room as them and by touching they things they contact.
Immune systems are not much different year round and neither are the virility of germs but the ease of transmission will change through the year as people move from outdoors to indoors.
How much a duh is this one.
People spread airborne illness more in winter because they spend more time inside, in contained airspace, among more people, than they do in summer.
For what it’s worth, NPR recently ran a segment (Talk of the Nation’s Science Friday) about influenza transmissivity as it relates to temperature and humidity. They found that transmissivity increases with colder, dryer environments. More here: http://www.sciencefriday.com/program/archives/200710195
and here:
http://pathogens.plosjournals.org/perlserv/?request=get-document&doi=10.1371%2Fjournal.ppat.0030151&ct=1