River blindness (Onchocerciasis) is spread by the female blackfly. A blackfly becomes infected when it bites an infected person. When the infected blackfly bites another person, it passes the larvae into that person. They move under the skin and form lumps, where they develop into adult worms. They may live up to 15 years and produce thousands of microfilariae that move through the tissues of the skin and eyes, causing river blindness.
Attribution: Straight Talk Foundation