Mr Mandela, 94, is said to be responding to treatment for the infection. He has spent three nights at a Pretoria military hospital since being admitted on the weekend for tests described as being “consistent for his age”.
Graça Machel, whom he married on his 80th birthday in 1998, said it was painful to see the anti-Apartheid leader “ageing”.
“I mean, this spirit and this sparkle, you see that somehow it’s fading,” she told eNews Channel Africa on Monday in her first interview since Mr Mandela went into hospital.
“To see him ageing, it’s something also which pains you … You understand and you know it has to happen,” she said.
Security is tight at the 1 Military Hospital in Pretoria, the biggest military hospital in the region, where Mr Mandela is said to be “comfortable” and not in any immediate danger. Officials are refusing to say when he might be released.
On Monday, Nosiviwe Mapisa-Nqakula, the defence minister, visited Mr Mandela and said he was “doing very, very well”.
President Jacob Zuma visited the elderly statesman in hospital Sunday morning and “found him comfortable, and in good care”, a spokesman said.
Ndileka Mandela, a granddaughter, told the TV network that Mr Mandela seems to have accepted his condition.
“I think he takes it in his strides, he has come to accept that it’s part of growing old, and it’s part of humanity as such,” she said. “At some point you will dependent on someone else, he has come to embrace it.”
Mr Mandela was last hospitalised in February for a minor surgical procedure to determine the cause of a long-standing abdominal complaint.
In January 2011, he spent two nights at a private hospital in Johannesburg for what officials initially described as tests but what turned out to be a serious respiratory infection.
Mr Mandela was diagnosed with tuberculosis in 1988 while incarcerated at Pollsmoor Prison in Cape Town, where he was moved after 18 years on Robben Island.
Mr Mandela has said he was fortunate the disease was diagnosed and cured before it reached an advanced stage, when TB can cause holes in the lung.
“I went to my friends in prison, Walter Sisulu and others, and told them that I was found to have the TB germ,” he told an international AIDS conference in 2004. “There were long faces drawn. My friends objected to me sharing my personal affairs.
“But I consoled them and told them that the doctors and hospital staff knew about my status and I therefore had no reason to hide this information from those close to me.”
(Re-printed from The Telegraph.com)