Aedes aegypti is the delivery system.

Aedes aegypti spreads dengue and Zika by injecting virus-laden saliva into you when it bites.

Here’s the short version: the mosquito picks up the virus by feeding on an infected person. That virus replicates inside the mosquito’s gut, then travels to its salivary glands. Next time it bites someone, it spits a little saliva (which contains anticoagulants) into the wound — and that saliva now contains the virus. You’