The United States Ebola patient who was flown in from Sierra Leone last week has taken a turn for the worse as hospital officials say his case has worsened to a critical condition.

A statement from the National Institutes of Health saidthe patient's status was changed from serious condition to critical condition.

The patient whose name and details have not been released, is a clinician working with Partners in Health, a Boston-based nonprofit organization. The group has been treating patients in Liberia and Sierra Leone since November.

The latest NIH patient is the 11th person with Ebola to be treated in the U.S while 2 patients in the U.S. have died - Thomas Eric Duncan and a doctor who was evacuated from Africa when he was critically ill.

Meanwhile, there are 11 other Partners in Health workers being brought to the United States for monitoring, one of whom has developed symptoms of Ebola and has been moved to a biocontainment unit in Nebraska. However, none of those being monitored has tested positive for Ebola.