When the autumn wind whistles outside, caring mothers tell their children, "Dress warmly! Otherwise you will catch a cold!" Rightly so? Can you actually "catch a chill" if you have cold feet or are freezing? We spoke with Susanne Hauswaldt from the Institute of Medical Microbiology and Hygiene at Lubeck University Hospital about this question.
As soon as it gets colder outside, your nose starts running. Photo: K.- P. Eagle/Photolia.com
> Do you get a cold more easily when you are cold?
S. Hauswaldt: There is no proof for the thesis that cold or drafts promote the outbreak of a viral infection. Statistically, more respiratory infections do indeed occur in colder temperatures. But it’s hard to prove whether that’s a direct effect of the cold or simply because people spend more time indoors when it’s cold, making it easier for viruses to spread from one person to another. There are surprisingly few studies that address this question. This is perhaps due to the fact that there are a number of additional influencing factors that are difficult to control. For example, the psyche surely plays a role. Someone who thinks they’ll catch a cold faster if they’re cold may already be more susceptible because of this attitude.
> Assuming cold would have an influence. What could it consist of?
S. Hauswaldt: There is a debate whether cold may weaken the immune system. In some studies it could actually be shown that it influences the natural killer cells. Unfortunately, however, these results were completely inconsistent: sometimes cold led to an increase in cells, then there was a slight decrease again. Cold is most likely to work by inhibiting local defenses. One hypothesis is that cooling the body surface leads to a reflex constriction of the vessels of the nasal mucosa. The reduction of blood flow could reduce the function of the nose as the first defense barrier of the immune system, because the leukocytes then have less access to the pathogens. It’s also possible that cold inhibits cilia, which play an important defense function in the respiratory system.
> What can you do to prevent viruses from reaching you in the first place? Are cold viruses more likely to be transmitted by direct contact, such as shaking hands, or by coughing on them??
S. Hauswaldt: Both are possible ways of transmission. Colds can be triggered by different viruses, which also have different transmission routes. Rhinoviruses, for example, are easily transmitted by smear infection, while parainfluenza viruses are more likely to be transmitted by droplet infection. So protect yourself from being coughed on – and wash your hands more often!
> How else can you protect yourself from "colds"?
S. Hauswaldt: It is important to have a healthy diet, not too much stress, enough exercise and seven to eight hours of regular sleep. It is quite clear that lack of sleep promotes a cold. Whether dressing warmly in winter protects against colds is, as I said, controversial. In case of doubt, however, I would rather advocate – especially since it certainly does no harm and the alternative is not very tempting .. .