A Texan health worker who treated Ebola victim Thomas Eric Duncan before he died is also infected with the virus, according to a preliminary test.
The worker, whose name was not given, wore full protective gear when treating Duncan on his second visit to a Dallas hospital, an official told reporters.
The new patient has been placed in an isolation ward and is said to be in a stable condition.
The worker reported a low-grade fever on Friday night and was isolated and referred for testing, officials said. Preliminary test results were received late on Saturday.
A car belonging to the infected health worker has been decontaminated, officials say.
If confirmed, this is the first known transmission of Ebola on US soil.
The current Ebola outbreak, concentrated in Liberia, Guinea and Sierra Leone, has resulted in more than 8,300 confirmed and suspected cases, and at least 4,033 deaths. (BBC)