The Centers for Disease Control and Prevention says a case of Ebola is confirmed in a man who was visiting a family member in California.
The agency said the man tested positive on Thursday at the University of California, San Diego Medical Center.
CDC Director Tom Frieden said the patient, who is from West Africa, is a man from the Sierra Leone area.
The man, who traveled to the US from Liberia on September 23, had previously visited relatives in the United States and was staying with his family in the US state of Texas, the agency said in a statement.
Frieden said there are no known contacts in the community, and that the man’s condition is stable.
Ebola is spreading rapidly in West Africa and there is no cure.
The virus has been killing people in West African countries for nearly two years and has forced the international community to work hard to contain it.
Since the outbreak began in Guinea, Liberia and Sierra Leone, more than 20,000 people have died and more than 2.3 million have been infected.
President Donald Trump said Wednesday that the CDC is working on a plan to isolate Ebola patients in the Dallas hospital and that a federal judge is scheduled to rule on the proposal Friday.
As the nation braces for a possible new outbreak, the Trump administration has been urging the public to limit travel and not to visit areas where the virus has spread, including in Liberia.