Onchocerca volvulus is a parasitic worm that causes a disease known as river blindness or onchocerciasis. This worm is transmitted to humans through the bites of infected blackflies, which are commonly found near fast-flowing rivers. Once inside the human body, the larvae develop into adult worms that can live for many years, leading to severe health issues. The infection can result in skin problems and, most notably, vision loss due to damage to the eyes. Efforts to control Onchocerca volvulus include mass drug administration programs using medications like ivermectin, which help reduce the worm's population and prevent transmission.