By Fiona Lloyd-Davies
Zelda Hansen, a wife and mother of three, is being held like a prisoner in South Africa. But she hasn't committed any crime. Zelda suffers from a deadly new form of tuberculosis that has devastated the lives of countless African families.
"It's like a prison. I'm found guilty for something I can't explain," Zelda told the BBC, whose cameras were allowed into her hospital for the first time.
Zelda is being held at Jose Pearson Hospital in Port Elizabeth, South Africa.
It is a hospital, but the guarded gates and a perimeter fence, ensnared by razor wire, tell a different story.
Her youngest son, Rosario, is just four years old.
"I can't hug him, I can't, you know, play with him, stuff that I used to do with the others when they were small," she says.
Zelda has been here for nearly two years and has no release date.
There is little to do during the endless wait in hospital
Her crime? To be suffering from Extreme Drug Resistant Tuberculosis or XDR-TB.
Tuberculosis is a world public health crisis and in South Africa it is been declared a national emergency.
Worldwide, it is estimated that nine million people contract standard TB every year and 90% of them live in the developing world.
South Africa has the highest rate of TB infection in the world. It is the epicentre of this TB crisis.
Despite her diagnosis, Zelda does not look ill.
It is one of the ironies of this new form of Drug Resistant TB, which is resistant to almost all of the drugs used to cure TB and so virtually untreatable.
This hospital used to have just Multi-Drug-Resistant TB (MDR-TB) patients here, but in 2006 a new, even more resistant strain, was discovered - XDR-TB.
The head of the hospital, Dr Bongani Lujabe, argues that with a highly infectious disease like this, isolation is the only way, especially when patients like Zelda may not even look ill.
"The patient may have a very dangerous strain of TB, yet they can be as fresh as you and me, and you may never be able to detect them or pick them out. These are patients that have been hospitalised purely for the sake of isolation and of prevention of spread," says Dr Lujabe.
Staff have a frightening vision of what might happen if these measures aren't taken.
"MDR and XTR, if not controlled, are almost like biological warfare against the population," says Dr Lujabe.
Zelda was one of several patients who escaped from the hospital in December 2007 to be with her family for Christmas, before being taken back.
The break-outs happen regularly, so the hospital has quadrupled the number of guards and beefed up its security fences.
Police are known to track down the escapees and forcibly return them to the facility.
HIV is the main reason there is so much TB in South Africa, where 19% of the population is HIV positive. People with a suppressed immune system are easy prey.
Zelda's husband and children wear masks when they visit
But there is so much of the disease now that everyone is at risk of TB, whether they are HIV positive or not.
Zelda does not have HIV and when she was diagnosed with ordinary TB, 20 months ago, she was prescribed the standard six months of antibiotics.
For many this treatment works, as long as they finish the entire course of drugs.
To ensure this, patients must go to a clinic every day and be watched taking their pills. But some patients feel better after two months and stop coming.
This failure to finish treatment can not only cause the TB bacteria take hold once more, but more importantly enables the bacteria to build resistance to the drugs.
Spike in cases
It is this "non-compliance" that has led the bacteria to mutate into two drug-resistant strains of MDR-TB and the much more dangerous strain XDR-TB. They are now found in 45 countries.
Protecting the public's health has become the focus in the battle against these new drug-resistant strains of TB.
It is why people with the new strains are being kept virtual prisoners, even if the cost is their personal freedom.
XDR TB is on the increase - in 2006 there was just one case at the Jose Pearson Hospital. Since then there have been more than 360.
Zelda was sent here when her standard TB converted into MDR, then when she was in hospital it mutated further to XDR-TB. She must stay until her sputum tests negative for TB.
Only one XDR patient has left this hospital permanently cured.
South Africa is suffering from a lack of doctors and nurses. Jose Pearson hospital finds recruiting extra hard since they started taking XDR-TB patients.
Few people want to work here - it is too dangerous.
The hospital finds it hard to recruit, as the work is so dangerous
Until new drugs and new tests are developed, there is little that can be done in the fight to stop this TB epidemic.
Professor Andreas Diacon in Cape Town is leading a drug trial.
It is imperative that new drugs are found to replace the old ones that have been used for the last 40 years.
These drugs are highly toxic and often cause painful side effects, some of which can be permanent, like deafness.
"It's a really tough situation for the patient and those who have to care for them," he says. "You really have to make sure that these patients do not infect others, because there is very little left to treat these people."
But Prof Diacon is realistic - drugs take many years to develop before they can be given to patients and you need three or four at the same time to combat XDR-TB.
When Zelda's husband Ricardo has enough money for petrol he takes their three boys to see her.
Zelda's husband and children are caught in the waiting game
They must wear masks to protect them against the deadly strain of TB.
She finds the separation almost too much to bear: "I've never been away from them for so long as I am now, never ever," she says.
Zelda must stay here until she has tested negative for TB. At the moment that seems an unreachable goal.
For patients like Zelda it is a prison sentence with no end.
This story will be featured in a series called "Survival", made for BBC World News by Rockhopper TV. "The deadly combination" will air on 15 November at 0810 and 1710 GMT and 16 November at 0110 and 1410 GMT.