A1. In the case of flu, high fever occurs suddenly compared to a common cold. The reason that high fever occurs suddenly is because the speed that viruses increase in the body is very fast. The speed is one virus becomes one million in a day. So the body tries to protect itself increasing the temperature of the body. Too much increase of virus prolongs the symptoms such as high fever or joint pain, and in the worst case it leads to a complication like pneumonia.
Q2. Where do flu viruses easily increase the most?
A2. The upper respiratory tract which is from the nose to the throat. The most suitable temperature that viruses increase is about 91.4 degree F (33 degree C) and the upper respiratory tract becomes this temperature inhaling cold air in winter.
Q3. What are the reasons that flu go around in winter?
(1) Dryness of the air
(2) Suitable temperature for viruses to increase
A3. Because the days are short. Exposure to the sun produces the substance which prevent the infection to the flu. The substance is vitamin D that is mostly produced through exposure to the sun. When vitamin D is activated by the exposure to the sun, cathelicidin antimicrobial peptide which beats the viruses is created in the immune cells.
Q4. To prevent the flu, how long should we be exposed to the sun a day?
(A) 20 minutes
(B) 2 hours
A. (A) 20 minutes. Proper exposure to the sun activates vitamin D. exposing only hands to the sun is still effective. Food containing plenty of vitamin D is Shiitake mushroom so it is good to go outside at least 20 minutes, eating Shiitake mushroom.