real or fictional sickness that knocks one down, like kung fuEdit
2010, Reginald Hill, Death's Jest-Book, Seal Books (→ISBN), page 148:
Young Mr Linford is too ill to attend. Possibly the advance guard of this new flu virus which is rife in London. Kung Flu, they call it, a play I assume on Kung Fu, because it knocks you down and leaves you helpless.
real sickness that originates from or is associated with AsiaEdit
1973, Views Letter:
The Asiatic virus is with us once again. This season, however, some witty physician calls it, "Kung flu."