News of a man in Dallas confirmed to have Ebola sounded the alarm in the United States last week. But Dr. Tom Frieden, director of the Centers for Disease Control, reassured the American people today that he was “quite confident” the United States wouldn’t suffer an outbreak.

Appearing on ABC’s “This Week,” Frieden said the United States would stop the deadly illness “in its tracks” because of the mechanisms put in place by the public health community. He did, however, express concern about the possible spread of the disease to other African countries.

Thomas Eric Duncan arrived in Dallas on Sept. 20 and began feeling ill several days later. On Tuesday, a blood test confirmed he had Ebola. Since then, there have been several reports of patients being monitored for Ebola-like symptoms, though they were ultimately false alarms.