Possession of flagellum is not a taxonomic feature. many different unrelated organisms have flagellum. euglena, zooflagellates but also some fungi or even human sperm cells.
Most people affected would live in China: 43 million or around 20 percent. At 32 million and 27 million affected people, Bangladesh and India would also be hit hard, as would be Vietnam, Indonesia, Thailand, the Philippines and Japan. In Europe, the Netherlands would theoretically be the most affected.
Many living organisms respond to things in the environment called Stimuli.