Answer:
Step-by-step explanation:
As a student, I think it has spread due to poor hygiene or practice. Most of the people I know that got it, received it from older family members. Sometimes there is also no rhyme or reason. I was exposed to a positive person twice (once in the lunch room and once in class) but with both of those experiences no one that was close contacted became positive. I think it is spread like the flu. If you stay home when you are sick then you will decrease the spread of it.