My concerns are a) controls to keep the disease out of the US are non existent b) our immigration policy and border is porous and Zebola and vector borne hemorrhagic diseases can enter easily. c) The patient zero's possible contacts are not being strictly quarantined. Zebola is not a common cold and is a game changer in any society.
The first confirmed case of “Spanish flu” was in March 1918.
By October 4 to 6 million Americans had the flu during that one month, and 200,000 of them died, that month. That’s leaving out the many millions elsewhere in the world.
I’m not sure it’s reasonable to call that a “slow spread.”
By comparison, we reportedly have <10,000 confirmed cases in Africa to date. That’s since December and in third world sanitary conditions and crowding. To my mind that rate of spread indicates it just isn’t very contagious from an epidemiological POV, or we’d have cases in the six or seven figure range by now, not in four figures.
Also, a couple of infected people got into Nigeria some time back, but they’re presently reporting only about 20 cases. I believe we can do a better job of controlling spread than Nigeria.