And a Spanish nurse who was treating an Ebola-stricken priest became infected herself, in the first case of Ebola transmission outside of West Africa.
But as the attention shifted to U.S. concerns and the situation in Europe, the death toll has continued to rise in West Africa, where medical teams are still scrambling to contain the deadly virus.
There are now more than 8,000 confirmed, suspected and probable cases of Ebola in Guinea, Liberia and Sierra Leone, according to World Health Organization figures released Wednesday, hours after Duncan's death in Dallas. Nearly 4,000 deaths have been reported in the region. The situation is especially dire in Sierra Leone, which this month reported a one-day death toll of 121, according to Reuters, and Liberia, where more than 2,000 Ebola deaths have been recorded.
Here's how the epidemic and the response looks in those countries now.
In Nigeria, the spread of Ebola appears to have been stopped; there have been no new cases in Africa's largest country since the end of August.
But in Sierra Leone, the Guardian reports that the rapid escalation of cases has drawn comparisons to how the virus spread in Liberia, where Duncan was reportedly infected.
"The disease has reached every county of Liberia," Anthony Banbury, head of U.N. Mission for Ebola Emergency Response, told the BBC. "It is clear that the international community has to have a rapid and very strong response to get this disease under control before it wreaks much more massive havoc in these countries and possibly other ones."