why do colds like the cold

December 14, 2005 10:44 AM

I have a question about colds. Why do folks get them when the weather gets colder? Don't germs and viruses and what not typically thrive in the heat? Do other illnesses thrive when it gets cold?
posted by zeoslap to Health & Fitness (21 answers total)

For a long time the cold weather=colds and flu connection was dismissed as an old wives tale sort of thing however just last month a study came out that showed there was a connection, I can't find the study now of course, if anyone else remembers it post a link.
posted by Cosine at 10:47 AM on December 14, 2005

* People hang out together in close contact more when it's cold, and stay inside more

* Does cold reduce your immune resistance?
posted by RustyBrooks at 10:47 AM on December 14, 2005

My (non-doctor) common sense tells me that A) people tend to gather together indoors more when it's cold outside, thereby coming into close contact more, and B) the runny noses caused by temperature transition make it just a bit easier to swap infected snot.
posted by luftmensch at 10:47 AM on December 14, 2005

People are inside more and in enclosed environments more. Not necessarily every individual, but most people, making transmission easier. Air circulation is worse in the winter. Those are the reasons I've always heard advanced.
posted by OmieWise at 10:47 AM on December 14, 2005

I read somewhere that the cold virus preffered temperature is lower than that of other viruses.
posted by MrMulan at 10:49 AM on December 14, 2005

Seasonal changes in humidity are also thought to play a role. Both freezing temperatures outdoors, and the general difference between cold outdoor air and heated indoor air cause low indoor humidity, resulting in drier mucuos membranes, which is thought to increace susceptibility to cold viruses.

Interestingly, they also think that school being in session might further contribute to cold season by bringing more kids into closer proximity for longer periods of time.

Google turns up some good info on this pretty easily, like this: http://www.niaid.nih.gov/factsheets/cold.htm
posted by Good Brain at 10:52 AM on December 14, 2005

Some related questions:

If colds are spread by people being inside more, than do colds spread a lot in the summer in very hot places like Phoenix and Las Vegas, where people stay inside because of the heat?

Do tropical countries with temperatures that don't vary throughout the year have cold and flu seasons?

Are the cold and flu seasons inverted in the southern hemisphere?
posted by driveler at 11:00 AM on December 14, 2005

My wife chimed in to support the idea that rapid changes in humidity and temperature contribute to weakening the immune system (appeal to authority, she's a master in public health)
posted by RustyBrooks at 11:01 AM on December 14, 2005

Perhaps your body is using more energy to maintain your body temperature and therefore has less to fight off viruses? I'm probably wrong. :)
posted by clarahamster at 11:11 AM on December 14, 2005

Here's a link to the article on CNN:

http://www.cnn.com/2005/HEALTH/11/14/cold.chill/index.html
posted by justkevin at 11:17 AM on December 14, 2005

My wife chimed in to support the idea that rapid changes in humidity and temperature contribute to weakening the immune system (appeal to authority, she's a master in public health)

...and every time you go inside or outside during the winter, you're undergoing a rapid change in humidity and temperature. Going from your 70° office to the 20° sidewalk for a cigarette can be a real shock to your system. Do that dozens of times a week and just try to stay healthy.
posted by nebulawindphone at 11:17 AM on December 14, 2005

I don't know about people in hot climates passing cold germs in A/C'ed rooms, but I can say that I often got awful summer colds in Boston, which I always blamed on going from our over-cooled office into the nasty heat and humidity of outside.

And now that I'm in more-or-less temperature-stable San Francisco, I haven't gotten a real cold in a year.
posted by occhiblu at 11:30 AM on December 14, 2005

A few years ago I heard a plausible explanation that was basically a mix of what clarahamster and RustyBrooks said. When you're outside, your body is using energy to keep warm, not to fight germs. I understand there are no germs outside in the cold, because germs die in cold temperatures. So your body is actually making a good decision in reverting resources to other functions. But then when you go inside, in the warm, where the germs are, it takes your body some time to warm up, realize it's in a germ-prone temperature, and start fighting germs again. It's in that transition time that the germs come in and make you sick.
posted by scottreynen at 11:39 AM on December 14, 2005

Here's what Cecil Adams has to say about it.
posted by dabradfo at 11:53 AM on December 14, 2005

I understand there are no germs outside in the cold, because germs die in cold temperatures.

More than likely you're going to pick up lots of bacteria and viruses throughout the day. Going from warm to cold doesn't mean there's some point when you get outside that germs attack you -- it's the shock to your system that weakens you.

I also have sinus issue when going between different temperatures/humidities and infection is a lot more likely when your sinuses are irritated. I have a humidifier at home for that reason.
posted by mikeh at 11:54 AM on December 14, 2005

I would also add a bit of epidemeology to the mix. I've read that isolated bases such as McMurdo usually have a mild epidemic every time they get newcomers. You spend 3 months from sep-nov building an immunity to sub-clinical infections in your local neighborhood. Then you spend three practically back-to-back holidays visiting with extended family and getting exposed to a new pack of cold/flu variants. In early Jan. you go back to working in close contact with people carrying viruses with them from all over the continent. So your odds of meeting up with something you don't have antibodies to fight are higher during and after the winter holliday seasons.

Also, stress is a major whammy on the immune system as well, and the combined stressors of winter weather, and family holidays probably are part of the problem.
posted by KirkJobSluder at 12:00 PM on December 14, 2005

"this study indicates an association between chilling and the development of cold symptoms in subjects with a history of frequent colds"
posted by stray at 1:27 PM on December 14, 2005

Interestingly, they also think that school being in session might further contribute to cold season by bringing more kids into closer proximity for longer periods of time.

That is probably why there is a cold and flu season in Florida as well. And I don't think cold and flu season in, say Minnesota, is any worse than it is in Florida.

If colds are spread by people being inside more, than do colds spread a lot in the summer in very hot places like Phoenix and Las Vegas, where people stay inside because of the heat?

Well school isn't in session so I don't know - there is a prime vector gone right there. Of course Air Conditioning is what originally set off legionnaire's disease, no?
posted by xetere at 1:38 PM on December 14, 2005

I've read that isolated bases such as McMurdo usually have a mild epidemic every time they get newcomers.

I've worked in isolated spots like that and it's true. After a while any new person coming in is Thypoid Mary.
posted by fshgrl at 6:14 PM on December 14, 2005

Are the cold and flu seasons inverted in the southern hemisphere?

No, because we all walk on our hands, so are immune to cold and flu.
posted by wilful at 7:42 PM on December 14, 2005

I'm not sure if it applies to both colds and flu, but I recall a very interesting story on NPR last winter about the value of giving schoolchildren (and only schoolchildren) flu shots. Kids in school are particularly prone to sharing germs, due to proximity, generally weaker immune systems and deplorable classroom hygiene. Then they take the germs home and share them with older people in the family and in general act as vectors.

There was anecdotal evidence of this in Japan, which was reinforced by the findings of a Harvard Medical School study released in August. Here's a more easily-understood piece about it from Slate.

Also, what mikeh said about humidiers - I too get sinus infections when the air is very dry, which seems to me an open invitation for a cold to get a toehold. I wonder if there is any difference between the number of colds now and before central heating became common?
posted by Jaie at 1:48 PM on December 16, 2005