why do we get sick when its cold

In terms of infectious illnesses, germs make you sick, not cold weather itself. You have to come in contact with
to catch a cold. And you need to be infected with viruses to contract the flu. Rhinoviruses peak in spring and fall, and influenza viruses peak in winter. While the cold canвt be the only reason, there is a connection between being chilled and getting sick: cold air may contribute to conditions that lead to illness. Some viruses are actually more likely to spread during cold weather. Rhinovirus (the cause of the common cold) replicates better at cooler temperatures, such as those found in the nose (33В to 35В Celsius) compared to the body core temperature (33В to 37В Celsius). However, found that immune system cells initiate a more robust antiviral defense at lung temperature versus nasal cavity temperature. This might mean that the body may not fight the virus as well if the temperature in the nose and upper airway is lowered by environmental cold.


Some assert that influenza virus is most stable in cool, dry temperatures. However, other studies show that the disease is also prevalent in humid, warm climates. Other factors suggested as potentially affecting immune response include sudden changes in temperature or the impact of dark and light cycles. But the bottom line is that cold doesnвt cause illness, although weather or other factors may weaken your ability to fight off illness. Posted by Mon, 12 Jan 2015 Scientists may finally be able to confirm the widely-held suspicion that bad weather can make you sick. While the common coldвs name seems to imply that cold weather is responsible for the nose-running, throat-burning misery, the scientific community has been unable to establish exactly how a chill in the air might lead to the snifflesвuntil now. Just last week, a team of scientists from Yale University announced their discovery that lower temperatures weaken the noseвs first line of immune defenses.


The researchers started out by modifying a strain of rhinovirusвthe kind of virus that causes most coldsвto infect mice. (The modification was necessary because most cold viruses that infect humans donвt seem to infect rodents). They then tested how well the cells that line mouse airways fought off the virus at different temperatures, finding that cooler temperatures meant a more sluggish immune response and a greater susceptibility to infection. Hereвs Carl Zimmer, reporting for the At body temperature, the cells responded with a sophisticated defense, sending out warning signals to uninfected cells around them. Those cells prepared an arsenal of antiviral proteins, which they used to destroy the rhinoviruses. But at a relatively cool 91. 4 degrees Fahrenheit, Dr. Iwasaki and her colleagues found, things changed.


The neighboring cells only managed a weak defense, allowing the rhinoviruses to invade them and multiply. This result pointed to an explanation for why rhinoviruses plague humans at low temperatures: In cool conditions, the immune system somehow falters. Previously, scientists thought the association between winter and colds might be more behavioral than biological: an increased number of people sharing air inside warm spaces could lead to more transmission of the virus. This study adds biological evidence to mix, revealing that cold weather actually hampers our defenses against rhinovirus infection. More work will need to be done to demonstrate that this phenomenon is true for living animals as well as for cells in a dishвand then to demonstrate it in humansвbut this study nevertheless provides an interesting clue to the mysterious connection between cold, and colds.

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