After emerging victorious from prison to lead South Africa to democracy and become a global icon, Nelson Mandela may have been stalked by his prison past in the years since freedom was won. Experts say that the tuberculosis he developed in the 1980s and the constant exposure to dust could be behind his recurrent lung infections. 

On June 8, Mandela was admitted to hospital for the fourth time in six months – most of these stays were for serious lung infections such as pneumonia. The presidency said Mandela (94) was admitted during the early hours of Saturday morning after experiencing breathing difficulties due to a recurring lung infection. 

According to pulmonologist Keertan Dheda of the University of Cape Town, Mandela's repeated lung infections could relate to him suffering from tuberculosis (TB) in 1988. The former anti-apartheid activist was diagnosed with the condition while serving part of his 27-year sentence in Pollsmoor prison in Cape Town. He was originally admitted to Tygerberg Hospital for a lung ailment, but TB was later diagnosed. 

Dheda said TB could permanently damage the airways and lung tissue and leave behind holes and scar tissue in which bacteria could accumulate. "People who previously had TB are much more prone to lung infections, which can lead to pneumonia at a later stage," he said.  

Lung specialist Elvis Irusen, from the University of Stellenbosch, said: "Even if TB is treated at a relatively early stage, it almost always still leaves damage in the lungs, as people mostly discover the TB only once they develop severe symptoms." 

Inhalation of dust
According to Dheda, Mandela's "chronic inhalation of dust" while working in a limestone quarry during his 18-year stay in prison on Robben Island could also have impaired the immunity of his lungs. "When such dust accumulates in your lungs, it can damage the immune cells, or macrophages, in the lungs, which has an impact on their ability to fight off future infections," he said. "The dust can also cause permanent damage to the airways and lead to the formation of scar tissue, which makes it hard to breathe and can reduce immunity."  

Dheda said such damage could be diagnosed with X-rays. "It is important to note that none of us, except for Mandela's doctors, have seen his X-rays, so we can only speculate."   

Irusen said lung infections were 15 times more common among patients of 90 and older and also 15 times more dangerous. 

"The main reason is that there is a general decline in the immune system's ability to fight off infections with age," he said. "Close to half of lung patients in their nineties also experience heart problems and kidney failure, which has a significant impact on their ability to recover. This combination is usually fatal – it has close to a 100% ­mortality rate."  

He said that when patients, as in Mandela's case, were readmitted repeatedly for lung infections, they were likely to build up resistance to the antibiotics used to fight off the bacteria that lead to such illnesses. "The resistant germs are much more dangerous and virulent, as well as harder to treat, as they have figured out how to fight the original antibiotic treatment that was used. Such patients, therefore, need two to three different types of antibiotic treatment to treat recurring infections."  

Infections take their toll onthe rest of the body
In March this year, Mandela developed a pleural effusion, or excessive fluid that fills the space surrounding the lungs, as a result of severe pneumonia. According to Irusen, such fluid could have accumulated because of pneumonia-related inflammation, or because Mandela's body could not handle the fluid properly due to heart or kidney failure. 

"When lung infections occur, the heart needs to work harder to pump blood and the infection often also damages the kidneys, which then do not properly filter waste products in the body, leading to muscles weakening and nerves not functioning well."  

While the presidency has confirmed that Mandela is breathing on his own, lung patients of his age often need breathing machines, or ventilators, to survive, said Irusen. 

"Technically, you can be kept alive indefinitely with a ventilator, as the machine does the breathing for you and provides you with oxygen. But it's not a pleasant experience."

Irusen said that because a ventilator was uncomfortable – a thick tube is put down your airway – patients were sedated. "They're therefore half asleep and not aware of what's going on around them. They may, for instance, pick up a word here and there, but take it out of context and become scared. We also give them paralysis medication to relax their chest muscles, but that has an impact on their ability to move their hands and feet, which makes the process even more uncomfortable. You could be asleep in the same position for months."  

Drug resistant bacteria sometimes "live" in ventilators, especially in intensive care units (ICUs) and then infect patients, resulting in secondary infections. 

"Many ICUs, public and private, are reluctant to admit patients above 70 years of age," Irusen said. "It's terrible to play God, but when the high costs of keeping people alive and the high mortality rates of older people are taken into consideration, it's a moral and ethical decision we have to take, or ICUs will have three-month-long waiting lists and be unable to save younger people with potentially longer lives ahead of them."