Flu

[josusan]

Why is flu more common in the winter

[Rabelais]

While it's known that flu is seasonal, it's not fully known why. Due to there being 2 winters on the globe, one in the northern and one in the southern hemisphere there are two peaks of influenza cases worldwide. The current thinking is that due to worse weather in the winter people stay indoors and are closer together for prolonged periods of time. This enhances the virus�s transmission. Also the virus will survive longer on doorknobs and surfaces etc. in colder conditions.
Secondly winter air tends to be cold and dry leading to mucus membranes in the upper respiratory track drying out. This is believed to decrease the body�s defences to viral infection.
The final theory is one that links Vitamin D levels with susceptibility to the virus. Exposure to sunlight makes the skin produce vitamin D, therefore in the winter levels are reduced. This was proposed in the 60's when large doses of Vitamin D were given in the form of cod liver oil and a general decrease in respiratory infections.

[Octavius]

Men get flu all year round and against all odds, manage to survive and strive on regardless. Sometimes we can even watch TV and drink beer whilst having flu.

It remains unclear why outbreaks of the flu occur seasonally rather than uniformly throughout the year, although the points above are possibilities. Another hypothesis one is that the virus has a natural cycle, or that seasonal deficiencies in vitamin B result due to a lack of sunlight and thus reduce our immunity to the virus.

Did you know that influenza (flu) was once known as influenza di freddo, meaning "influence of the cold"?