06 December, 2005

Conventional wisdom

For years I've been hearing the bullshit hypothesis that there are more colds in winter because people tend to spend more time indoors in the winter and thus are more likely to transmit infections. This makes very little sense, especially in cities. I've also been hearing there is "no evidence that exposure to cold weather makes you more likely to get a cold". This is more likely a failure of the crappy case-control studies performed to measure the effect. I'm much happier with the "cold weather causes immunosuppression" hypothesis, which I'm gratified to read is favored by some "rhinologists"*. From Eccles, R., "An explanation for the seasonality of acute upper respiratory tract viral infections." Acta oto-laryngologica, Mar. 2002:
Despite a great increase in our understanding of the molecular biology of the viruses associated with acute upper respiratory tract viral infections (URTIs) there is a remarkable lack of knowledge and ideas about why URTI should exhibit a seasonal incidence. Most publications in this area either acknowledge a complete lack of any explanation for the seasonality of URTI or put forward an explanation relating to an increased "crowding" of susceptible persons in winter. This review will discuss some of the ideas concerning the seasonality of URTI and put forward a new hypothesis for discussion, namely that seasonal exposure to cold air causes an increase in the incidence of URTI due to cooling of the nasal airway. The hypothesis is supported by literature reports demonstrating that inhalation of cold air causes cooling of the nasal epithelium, and that this reduction in nasal temperature is sufficient to inhibit respiratory defences against infection such as mucociliary clearance and the phagocytic activity of leukocytes. A case is also made to suggest that warming of the nasal airway during fever and nasal congestion may help to resolve a current URTI.

* Unfortunately, they do not actually study rhinos, and the journal "Rhinology" is not full of papers on rhino anatomy and dietary habits.


This might explain why my cold cure works. When I feel a cold coming on, I take a swim in San Francisco Bay (now 54 degrees F, well below the 78F of a cool pool) and then take a long hot sauna. I guess it's the sauna doing the work. 

Posted by hedgehog

Great.Scientific proof that waiting for my bus for 40 minutes yesterday, because it simply never came, and then getting on to the crowded, sneezy, coughy next bus, probably actually was  bad for me.

I actually always thought cold->suppressed immunofunction was the accepted conventional scientific wisdom. I did not know that heating the nostrils back up again would help, though.

I think there's a different but related effect--not when one is getting the first nasal-throat infection of a cold, but when the cold is turning into bronchitis. I could never come up with a good reason why, but when I had bronchitis in cold places, it always seemed to me that breathing in very cold air actually hurt. But this article reminds me that the lungs are lined with hairy epithelia, and it's quite possible that their function is temperature dependant. If they're already inflamed from a bad case of bronchitis, they might be even more temperature-sensitive. An interesting avenue of research. . .I'll leave the rhinology-persual to the real rhinocrats though. :-)

hedgehog: Your cure inspires another wacky hypothesis for testing. Let's see--allergies are basically colds without infection, yes? All that anti-cold machinery getting turned on for some harmless pollen or not so harmless soot. The defense is half the unpleasantness. Maybe your cold swim is like a stop button that simultaneously shuts down the nasal immune response function while churning out tons of adrenaline and other exercise-mediated response functions. Then the Sauna is like a restart button that gets the immune function going again--but this time supplemented by all that adrenaline and stuff, so it can be more efficient and not quite so gooey and messy.

Of course, I have no idea how we'd go about testing this. Get a bunch of similarly healthy people, expose them all to rhinoviruses, dump some of them in the bay for swimming before sauna, some of them into a cold water tank without swimming before sauna, and send of them straight to sauna, while another set go home and watch TV. Sounds expensive.  

Posted by Saheli

Because I am not nearly as interested as you in actually investigating the reality of how viri infect people, I have instead relied on a little story that I like to tell myself. The viri are askeered. First you lower your body temperature by a couple-few degrees in the water, down to borderline dangerous hypothermia. The "cold" viruses are like, hey, cool, this is my kind of house. Let's chill here. Then you fake them out with the sauna. It's a synthetic fever, boosting body temp by maybe 5 degrees F in a half an hour. Viri are like, fuck that, I'm finding a regular house. This place is super-freaky. So they up and leave.

Only problem is the hypothermia, petrochemicals, E. coli, mating sea lions, and dead bodies in the Bay are probably not good for your health anyway, so maybe a cold's not so bad. 

Posted by hedgehog

I was actually thinking the petrochemicals mght act as an antiseptic. I was going to ask about the E. Coli, dead bodies and mating sea lions but I didn't want to be all negative like. As for the hypothermia, I figured hedgehogs are just really good at staying warm.

Super-freaky works with unwanted guests, unless the guests themselves are even freakier.  

Posted by Saheli

"crappy case-control studies"

Could you please explain what you find crappy in these studies? 

Posted by Apokrif

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