DALLAS (AP) — Hospital officials say the man being treated for Ebola in Dallas is showing improved liver function, though he remains in critical condition.

Texas Health Presbyterian Hospital released a statement Tuesday saying Thomas Eric Duncan is on a ventilator and is receiving kidney dialysis. The hospital says his liver function improved after declining over the weekend, but warns that his condition could vary in the coming days.

Duncan is from Liberia, and he fell ill after traveling from the Ebola-ravaged country to Dallas two weeks ago. He is the first person to be diagnosed in the U.S. with Ebola.

Duncan has been hospitalized since Sept. 28. Federal and local officials are monitoring nearly 50 people who had varying degrees of contact with Duncan before his hospitalization.