We have covered this topic briefly in class, and it is the concept that most of us know already! When I thought about this, I came to my own conclusion that the chance of viral infection may get increased because of bronchodilation, which is induced by activation of the sympathetic branch of the autonomic nervous system versus cold temperature. I presumed that this increase in diameter of the air passage may increase the susceptibility to viral infection.
And.. I am partially right on this! You could get a cold from a rhinovirus, not from the cold temperature. The cold temperature does not compromise the immune system; however, these two factors are correlated because people spend more time inside in the winter time. It means there will be an increase in interpersonal interactions; thereby increase in chance of viral infection. I also realized that the viral infectivity gets increased as the temperature and humidity decrease. It is simply because the viral activity is most active at low humidity and cold temperature. It implicated the importance of 'nose breathing,' which allows the inhaled air to get turbinated (warm + humidify); mouth breathers would be at risk of developing acute and chronic bacterial and viral infections by skipping this crucial process.
References:
Arundel AV, Sterling EM, Biggin JH, Sterling TD. 1986. Indirect health effects of relative humidity in indoor environments. Environ. Heal.Perspect. 65: 351-365.
Very interesting. I don't think I have ever thought about getting a cold in this context. I just live by what my mom would always tell me growing up, "Put a jacket on before you go outside or your gonna catch a cold!" This however changes the way I view that statement. Transmission of the rhinovirus is what actually gives you the cold, and it makes sense that because the weather outside during the winter is colder, humans would naturally spend more time inside where it is warmer. This increased time spent indoors around other potentially ill individuals would dramatically increase the chance of catching the rhinovirus from someone else. Additionally, since you said that virus infectivity increases as humidity decreases, I can definitely see the application to us in Colorado since we are constantly in a low humidity state.
ReplyDeleteI would have to agree. I find this article quite interesting. I was always under the impression that cold air would weaken your immune system some way thus leading to being sick. I never thought of how a decrease in humidity and increased temperature can increase the viral activity. After thinking about this, it makes sense and now I see why people get sick so much easier in winter. I guess I need to lower the temperature of my house and increase the humidity! I am curious to what extent the virus activity is at its peak? Is there a certain temperature or humidity that virus' thrive in? I also wonder if certain places that have increased amounts of humidity show a decreased amount of viral infections as compared to somewhere that is drier, such as Colorado. Now that cold is coming and we are in class all the time, we better crank up the Vitamin C, sneeze and cough in our sleeves and wash our hands so our whole class doesn't get sick! We do not have the time for the sniffles!
ReplyDeleteWhat a simple concept to explain a common misconception. I think it would be fascinating to perform an epidemiological study and see if, as Kristin suggested, you see a lower rate of infection in places with higher humidity. I would hypothesis that more moisture in the air intensifies the sensation of the cold outside which would drive people inside more often. If you could compare time spent indoors against the number of times they catch the sniffles in a given winter, I think there is a strong chance you will discover a correlation. I wonder why the humidity has an impact on the virus in the first place. I would think that increasing the humidity would increase the time the virus is suspended in the air and maybe improve the chance it will get picked up in the first place. Thank you for clearing the cause of the cold up for us Minwoo now we just need to figure out why those two factors help the virus spread. We have finals in a week after all.
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