The worst of the Ebola outbreak has passed, according to the presidents of Guinea, Liberia and Sierra Leone, who met with President Barack Obama at the White House this month.

“In Liberia right now, there are zero cases," Obama noted. "In Sierra Leone and Guinea combined, there were fewer than 40 new cases last week, and that’s the lowest number in a year. Now we are focused on a shared goal —that is, to getting to zero.  We can’t be complacent.  This virus is unpredictable.  We have to be vigilant, and the international community has to remain fully engaged in a partnership with these three countries until there are no cases of Ebola in these countries. Health systems also have to be rebuilt to meet daily needs.”

In an exclusive interview, Sierra Leone's President Ernest Bai Koroma spoke with Straight Talk Africa’s Shaka Ssali, who asked what lessons the president had learned that would hlep him improve health care in his country and throughout the continent.

"A good number stopped seeking medical attention from the hospitals and clinics," Koroma said, "so I think one of the lessons we have learned, which we are trying to quickly implement, is the establishment of disease control centers in our countries. I believe with the establishment of centers of excellence of disease control we will be able to fight back whenever we have a future outbreak. And it will also help us to strengthen the training of health officers and maybe put in place structures that will clearly define protocols and processes in the existing health systems.”

Prior to the Ebola outbreak, the economies of Guinea, Sierra Leone and Liberia were growing steadily.

“The response to our call was positive," said Liberian President Ellen Johnson Sirleaf, "and everyone said these countries deserve the help, not only because we’ve been through this, but because we have to prepare our health systems to have the resistance and the capacity to respond to this. Because this is not a West Africa threat, it’s a global threat.”

The leaders return to West Africa with assurances from the United States that it fully supports efforts to help rebuild their economies and their Ebola-stressed health systems.

WATCH: An interview with Liberian President Ellen Johnson Sirleaf.