Transfer (Intiqal)

210. If the blood of a human being, or of an animal whose blood gushes forth when its large vein is cut, is sucked by an insect, normally known to be bloodless, and it becomes part of its body, the blood becomes Pak. This process is called Intiqal.
But when a blood-sucking leech sucks human blood during some treatment, it will be najis, because it is not considered as part of its body – it is considered as human blood.

211. If one kills a mosquito which has sat on one's body, and blood which it has sucked comes out, it will be considered Pak, as it was destined to be its part, even if the time gap between its sucking and it being killed be very small. However, as a rec ommended precaution, one should avoid such blood.