In nearly 20 years with the Centers for Disease Control and Prevention, Rear Adm. Nancy Knight, director of the agency’s global health protection division, has led the development, coordination and implementation of public health policies and programs in countries including Nigeria, Kenya and South Africa. Before joining the C.D.C., Dr. Knight trained as a family physician and before going to medical school she was a Peace Corps volunteer in Lesotho.

In 2008, Dr. Knight helped start Nigeria’s Field Epidemiology Training Program, training “disease detectives” to identify diseases and how to respond to them. When Ebola came to Lagos, she returned to Nigeria and worked with the government and the “detectives” to deal with the disease.

“Those people we trained were instrumental in fighting Ebola because they were leading the effort on the ground, looking at daily cases and running that response within those communities,” she said.

Dr. Knight talked about the coronavirus, what travelers can do to avoid it and how the C.D.C. works with governments and other groups around the world to help countries stay prepared for the possibility of an outbreak of a contagious disease, and to tackle those diseases when they occur.