Former U.S. president George H.W. Bush remained in intensive care at a Houston hospital, but his condition "continues to improve," a Bush family spokesman said Friday.
"President Bush remains in the intensive care unit at Methodist Hospital, where he continues to improve," family spokesman Jim McGrath said in a statement, adding that the ex-president's exchanges with medical staff now included singing.
The Bush family and the doctors are "cautiously optimistic that the current course of treatment will be effective," McGrath said.
Bush, 88, who had been hospitalized at the Houston hospital for about a month with bronchitis, has been in intensive care since Sunday and was now on a liquids-only diet.
McGrath, who said Wednesday that a fever that kept Bush at the hospital over Christmas had gone away, later corrected himself, saying that the fever worsened.
"It's an elevated fever, so it's actually gone up on the last day or two," he said. "It's a stubborn fever that won't go away."
Doctors at Methodist Hospital have run tests, but still haven't nailed down a cause for the fever, McGrath added.
Bush was initially admitted to the hospital on Nov. 23, and has remained there due to what his spokesman described as a "lingering cough."
Jean Becker, Bush's chief of staff, said Thursday evening that Bush was getting excellent medical treatment and would advise people to "put the harps back in the closet."
But Becker also pointed out that the ex-president was sick and would likely remain in the hospital for a while after a "terrible case of bronchitis which then triggered a series of complications."
Bush served as the 41st president of the United States from 1989 to 1993.