I think it’s this but i might be wrong i’m not 100% sure
pharmacological
Playing outdoor games together
hope you have a good day =)
Cus it’s red muhahaha hhhhh
protozans is your answer thats why they say wash your hands before you eat or when you come home from a day outside cause the bad bacteria goes in your body and then many problems happen. and thats how sicknesses spread or diseases.