When an Aedes aegypti mosquito bites you, she – because only the females, which need blood as nutrients for their offspring, bite – will probe your skin with her proboscis as many as 20 times. Two pairs of sharp cutting edges, the fascicle, break the skin and then search for a blood vessel, withdrawing and re-entering until a suitable target is found. When the blood starts to flow, a salivary tube delivers a protein that stops it clotting. The mosquito holds still and then begins to suck; in 90 seconds’ time, she feels full, and stops. And then, if you are in parts of South and Central America and bang out of luck, you will have Zika.
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