For prevention: use a "mosquito kam kong" repellant machine - good thing is no chemical, just the sound will scare the mosquito.
For cure: I am using a mosquito cream bought in Sogo 6/F - baby corner - I don't have the name on hand now but there is only one - like toothpaste shape, orange color from France, around $80. Very effective in reducing swollen and stop itchy. Also it's made from natural ingredients.