#Ebola is spread by direct contact w/bodily fluids of a sick person or exposure to contaminated objects, like needles pic.twitter.com/lVjLoWYBki
— CDC (@CDCgov) September 30, 2014
After confirming the first U.S. case of Ebola virus, the federal Centers for Disease Control and Prevention has stepped up its public education efforts, including tweets like the one above about how Ebola is spread.
But we've still got questions, lots of questions. That's especially true for people who live in Dallas, where the man fell ill. There's been a lot of concern expressed in social media about that fact that the man was turned away the first time he went to the hospital, and how many people may have been exposed as a result. This conversation on Reddit is a good reflection the speculation:

Much of the online debate has centered on air travel, and why the man, who arrived in Dallas from Liberia on Sept. 20, wasn't asked about recent travel the first time he went to the hospital with symptoms on Sept. 26:
@CNN How many ER's will examine & release #Ebola patients like Dallas? Every ER must ask "Been to Africa?" at registration, WITHOUT FAIL!
— Richard Stiller (@richard_stiller) October 1, 2014
All 3 DFR EMS crew members tested negative for Ebola. Sent home. Will be closely monitored for the next 21 days.
— City of Dallas (@CityOfDallas) October 1, 2014
The EMTs who took the man to the hospital the second time are being monitored, but it's still not clear who else was exposed. On Monday afternoon, Texas Gov. Rick Perry said Monday that children in Dallas were in contact with the Liberian traveler. Are people who were exposed being quarantined at home? How are they being monitored?
Science magazine's Jon Cohen is wondering how many people enter the U.S. each week who have recently been in one of the African countries where Ebola is epidemic. Knowing that number could help calculate the odds of more cases here.
Our unasked questions for Tom Frieden at yesterday's #Ebola press conference: http://t.co/tGskX5Ken6
— Jon Cohen (@sciencecohen) October 1, 2014
And though in the United States the focus is very much on this one case, Canadian journalist Helen Branswell points out that the best way to reduce the risk to Americans — and everyone else in the world — is to help quickly end the epidemic in Africa.
"The best way to sum it up in my mind is a good offense in West Africa is the best defence for everyone else." Dr. Kamran Khan, a Toronto-based researcher who uses global flight data to predict spread of infectious diseases, told Branswell. "And that's ultimately what has to happen."
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If the world doesn't stop #Ebola in West Africa, the mathematics of risk for the globe will shift. For reals. http://t.co/jiJI3H74fA
— Helen Branswell (@HelenBranswell) October 1, 2014