Varies: There is no specific dangerous heart rate during exercise. How fast your heart beats with exercise depends on a number of factors, especially your conditioning. If you are healthy, a heart reate in the 170's or even higher may be ok and tolerated.
Motion sickness caused by video games, sometimes called simulator sickness, is caused when there is a disconnect between what your eyes are seeing and what your body is feeling.
African sleeping sickness is caused by protozoa in the Trypanosoma genus. These organisms are carried by the tsetse fly and transmitted to humans via tsetse fly bites. According to the World Health Organization, Trypanosoma brucei gambiense causes more than 90 percent of African sleeping sickness cases.