Former US President George H W Bush is in a hospital intensive care unit with an infection, a week after the death of his wife, Barbara.
In a statement, a family spokesman said he had contracted an infection that spread to his blood, but was “responding to treatments”.
The 93-year-old was admitted to hospital in Houston on Sunday morning.
He was president from 1989-93 and his son, George W Bush, went on to serve in the same role.
Barbara Bush, the only woman to see both her husband and her son sworn in as US president, died last Tuesday and was laid to rest on Saturday.
The couple had been married for 73 years.
After her death, Mr Bush said of her: “We have faith she is in heaven and we know that life will go on, as she would have it. So cross the Bushes off your worry list.”
Who is George H W Bush?
Mr Bush became the 41st US president after serving eight years as vice-president to Ronald Reagan.
His term in office between 1989 and 1993 was defined by foreign policy, coming at a time when communism was collapsing in Eastern Europe.
Mr Bush built a successful international coalition to end Saddam Hussein’s occupation of Kuwait in the first Iraq War.
But despite achieving popularity ratings of 90%, he was accused of neglecting domestic affairs and was defeated by Bill Clinton in the 1992 presidential election.