They don’t have to shut anything down. Think about it. 5 malls across the country get hit, say the 2 biggest and the other 3 are Smallville/Mayberry types. Result? Lots of sick people, by the time the ‘system’ realize it is ebola how many will be infected? Here is where it gets scarry, how many people will attempt to stop going out in public? How many people will not go to work? These are the ripples. I agree multiple attacks would be worse, say 100 malls on the biggest shopping day of the year? Then wait and hit the power grid during the big January ice storm that always hits in the northeast, the most heavily populated part of the country. If, very big if, they really have their stuff together an emp strike during January would be bad.
So worst case, they now have several different types of chemical munitions, possibly some dirty bombs, and these ebola martards. They could hit us with dozens of different attacks over a holliday weakend and wreak havoc.