Meet America's last iron lung users.

Once the most feared virus on the planet, polio was wiped out in the United States in in 1979 thanks to the success of the vaccine.

But while that's good news for the world, a few polio survivors who rely on iron lungs to help them breathe are struggling to cope with their decades-old machines which are no longer covered by their insurance or serviced by manufacturers who stopped production in the 1960s.

Paul Alexander, 70, of Dallas, is one of just a handful of people around the world who needs the iron lung to survive.

Paul Alexander, 70, of Dallas, (pictured) is one of just a handful of people around the world who still relies on an iron lung to help him breathe

Today, he spends almost every moment in the device after contracting polio as a five-year-old in 1952

Today, he spends almost every moment in the device after contracting polio as a five-year-old in 1952.

But he faced a crisis in 2015 when the machine began to malfunction. With no support from the manufacturers, his insurance companies, and parts only rarely available at great cost, he put out a YouTube video appealing for help.

Thankfully, Brady Richards, who runs the Environmental Testing Laboratory, and is a keen hobbyist mechanic saw the appeal and reached out.

'I looked for years to find someone who knew how to work on iron lungs,' Alexander told Gizmodo. 'Brady Richards, it's a miracle that I found him.'

Richards said when he brought the iron lung into his shop for repairs, his younger employees had never heard of it.

The respirator, which resembles a terrifying metal coffin, requires patients to lie down inside, with the device fastened tightly around their neck. It works by creating a vacuum to mechanically draw in oxygen to the lungs for patients whose central nervous system and respiratory function were ravaged by polio.

'When we first brought the tube into the shop, one of my younger employees asked me what I was doing with these smoker grills,' Richards said.

He faced a crisis in 2015 when the machine began to malfunction. With no support from the manufacturers, his insurance companies, and parts only rarely available at great cost, he put out a YouTube video appealing for help (pictured)

The dated technology is wearing out, with fewer parts available and little support from the former manufacturers

Alexander's iron lung contains metal portholes and is painted in a bright yellow color

Despite being almost entirely paralyzed below the neck by the virus, Alexander went on to achieve his dream of becoming a trial lawyer.

'When I transferred to University of Texas, they were horrified to think that I was going to bring my iron lung down, but I did, and I put it in the dorm, and I lived in the dorm with my iron lung,' said Alexander, who used to represent clients from a wheelchair.

'I had a thousand friends before it was over with, who all wanted to find out what's that guy downstairs with a head sticking out of a machine doing here?'

A SHORT HISTORY OF THE IRON LUNG An iron lung is a non-invasive negative-pressure ventilator, used to artificially maintain respiration during an acute polio infection. They were first used in the 1920s and work by producing pressure on the lungs that causes them to expand and contract so that patients can breathe. In most cases it would only be used for one or two weeks, until the patient could breathe independently, but some polio survivors with permanent respiratory paralysis rely on them daily. They are now all but obsolete, replaced by positive-pressure ventilators such as modern day respirators. Advertisement

Even as his symptoms worsened over recent years, confining him to the iron lung for the majority of the day, he has remained upbeat and keeps busy - he's currently working on a memoir, typing it out with a pen attached to a plastic wand he holds in his teeth.

Ma rtha Ann Lillard's crippling illness has made her a prisoner in her own home for more than 60 years.

Paralyzed by polio at age five, the Oklahoma woman has spent most of her life encased in a 1940s respirator which breathes for her.

She says that modern alternatives to the iron lung are simply not as efficient or comfortable.

'I can't use other types of ventilators because of inflammation that comes with Polio,' said the 69-year-old. 'I could be more rested if I stayed in the lung full time. But I choose to be up as much as possible.'

'Some people have said I’d rather die than leave my iron lung, and it makes it sound like I’m not trying to be modern, and it’s not like that at all,' she told NBC News.

'It feels wonderful, actually, if you’re not breathing well. When I was first put into it, it was such a relief. It makes all the difference when you’re not breathing.'

Lillard, of Texas, has learned to live with her disease.

She lies on a goose down comforter inside the 800-pound respirator in which she’s enclosed with an airtight seal. Her neck and head sticks out of a foam collar.

There are switches inside to allow her to roll a tray-like cot in and out.

A polio patient receives treatment inside an iron lung in France in 1939

Iron lungs became common place in hospitals in the 1940s and 50s as the only way to keep patients alive

Lillard was infected with polio at her fifth birthday party at the Joyland Amusement Park, Texas, on June 8, 1953. What was first dismissed as just a cold, became increasingly worse until she couldn't raise her head from the pillow. Doctors confirmed the worst.

'The night before I was paralyzed, the neighbor children ate out of the same bowl of pancake batter that I did,' Lillard said. 'They just had to pray that nobody got it.'

She also has bent back from scoliosis which doctors couldn't operate on because polio patients can die on anesthesia.

Today she lives alone aside from her three beagles and 20 geckos, although she has a helper come in.

WHAT IS POLIO? Polio is an infectious viral disease that affects the central nervous system respiratory function and can cause muscle weakness and paralysis. It is transmitted through contaminated water and food or contact with an infected person. It has largely been eradicated around the world after widespread use of the vaccine which came into use in the 1950s. The disease remains endemic in just four countries today: Nigeria, Pakistan and Afghanistan. Advertisement

Like all the iron lung users left today, she owns her iron lung, after Respironics, who inherited responsibility for the devices in a series of mergers, gave everyone a choice in 2004; upgrade to more modern respirators or accept full ownership and responsibility for the iron lung - and all its repairs.

The machines were actually manufactured by March of Dimes which produced the last iron lung in the 1960s.

But ownership means finding someone to repair them.

Lillard owns two iron lungs - one as backup.

They run on a fan belt motor that friends help patch together with car parts when it breaks.

Yet she admits she lives in constant fear of suffering a blackout which means her iron lung would lose power and she could die in her sleep.

Brian Tiburzi, executive director of Post-Polio Health International (PPHI), estimated that of the 350,000 to 500,000 polio survivors in the US today, less than ten were still using iron lungs.

'Part of it is just habit,' he told DailyMail.com when asked why those few were so reluctant to use more modern, portable options, such as the chest cuirass which is a much smaller device that is held against the chest but works in a similar fashion.

'That's sort of what they have been used to all their life. Some people also use them because they have trouble with the masks, some leak, some people get sores, or find them uncomfortable to wear.

'The vast majority of switched.'

He added that the announcement by Respironics in 2004 meant 'they were sort of told they were on their own.'

Tiburzi said that many polio survivors simply couldn't understand the anti-vaccination movement, and why anyone would risk the health of their kids.

The last big outbreak of polio in the US took place in 1952, which left 3,145 dead and 21,269 paralyzed (pictured is an iron lung being examined in an undated photo)

'Many polio survivors have strong opinions on that. They have contracted a disease that affected them in profound ways that is now preventable.

'People think it's lunacy you wouldn't take these simple steps to protect yourself.'

The last big outbreak of polio in the US took place in 1952, which left 3,145 dead and 21,269 paralyzed.

At that time, iron lungs became common place in hospitals as the only way to keep patients alive.

In 1955, Jonas Salk developed a vaccine which was so successful that the last wild case of polio in the US was in 1979.

There have been a small number of cases reported Afghanistan, Nigeria, and Pakistan where conflicts have disrupted the vaccination process.

But with the rise of the anti-vaccination movement in some states, it's possible that the US could be facing its first new outbreak in almost 40 years.

Lillard, who considers herself an anomaly in a U.S. society that barely remembers the scourge of polio, wants to make sure that people never forget.

'I think the word is to get your child vaccinated. Why would we let somebody have to go back through that again?' she said.