1) What is the likelihood of harm?
2) If harm occurs, what is the cost?
3) What is the cost of preventing harm, including the opportunity cost?
And allocate resources accordingly. In this case:
1) Extremely low. Approx. 3 people in the US have Ebola; all were in West Africa or treated someone already very ill. Nobody else in the US has been infected by these people (again, except someone providing health care to one of them). You are at much greater risk of heart disease, cancer, traffic accidents, hospital error, crime, and probably even lightening strikes and bee stings.
2) The cost is very high, including a substantial risk of death.
3) The cost is easily affordable for the US, but the opportunity cost is higher: The United States and the world have limited health care resources. For example, there's a good chance that many of the resources (doctors and money) would save many more lives and better protect US citizens by addressing heart disease (via prevention, treatment, or research) or controlling the outbreak in W. Africa than by responding to public panic.
I think you'll find that many experts in these fields will say that the panic is the greatest risk, greater than the disease.