Good subject and one that has baffled me. In my case i was born and raised in the UK and came to Asia in my 20's. Whilst i lived in UK i would get a bad cold at least 2 times a year which would leave me useless for a few days. I also had a problem with allergies which would leave me with swollen eyes for about a week. Since i moved permanently from Hong Kong to the Philippines i have had a few colds but nothing that has kept me in bed all day.
Will probably get a cold tomorrow and be bed ridden for a week