Discrimination for peole Exposed to Ebola

I find it funny that if you are exposed to Ebola by living around someone with Ebola in the US you must be quarantined for 21 days. I find it funny because if you live with someone who has Ebola in Africa and come to the US then you simply need to have your temperature taken at the airport then you are free to go.

Even if you have direct contact with full blown Ebola patients as doctors are in contact, you are not quarantined.

Why does the average everyday American get discriminated against in such a way?