ATLANTA (AP) — An American woman treated for the Ebola virus at Emory University Hospital said health care workers continue to learn more about the disease she contracted in 2014 while volunteering in the west African country of Liberia.

Nancy Writebol addressed nursing students in Atlanta on Friday, about two years after she arrived at the university’s hospital on a stretcher for treatment in a specialized unit for contagious diseases.

“Vaccinations are being worked on, (the experimental drug) ZMapp is being perfected and studies are going forward,” Writebol said in an interview after speaking to students. “We’re encouraged by that.”

More than 11,000 people in West Africa died of the virus starting in 2014, according to the World Health Organization. Writebol was the second American to arrive at Emory after contracting the disease while working at a Liberian hospital. Her duties included helping disinfect doctors and nurses who worked with Ebola patients.

Four Americans were treated and recovered from the disease that summer at Emory.

After recovering, Writebol returned to Liberia in March 2015 as a volunteer with the North Carolina-based charity SIM along with her husband, David.

Writebol said since returning she sees evidence that people recognize the importance of containing possible cases of Ebola. The WHO announced in June that the most recent outbreaks in Liberia and Guinea had ended and continues to monitor the countries.

Continued research on all infectious diseases will prevent their spread, Writebol said.

“If it’s not Ebola, it’s going to be something else,” she added. “It’s going to be the Zika. It’s going to be some other disease that we need to be aware of and not wait so long to address.”

Writebol told nursing students starting a new school year that they should follow the example set by health care workers who treated her in Emory’s isolation unit, particularly the 21 nurses who offered pedicures, remembered her favorite drink of V8 and comforted her family members.

“To the Ebola team of nurses: You are the best,” she said. “Students, I challenge you. Be the best of the best. Stand in the gap. Don’t be afraid. Wear that uniform with pride and serve the people that come through the door.”