A handful of polio survivors who have spent decades inside so-called iron lungs, have spoken of their existence trapped in ageing machines that have all but disappeared.

“There are only two or three of us left,” said 70-year-old Paul Alexander. Speaking from Texas, he added: “I’ve tried all the ventilators available and this one is the best. It feels like a more natural way of breathing.”

The battle against polio has been one of the great success stories of recent years.

While cases of the crippling disease still occur in countries such as Laos, Syria and the Democratic Republic of the Congo, it remains endemic in just three - Afghanistan, Pakistan and Nigeria. In the US, it was wiped out in 1979, thanks to the anti-polio vaccine.

In the 1950s, polio outbreaks caused more than 15,000 cases of paralysis each year, according to the Centres for Disease Control. Iron lung machines - pressurised cylinders that draw oxygen into a person’s lungs by creating a vacuum - were once commonplace.

Most people would only need to use the machines for a week or two until they could breathe on their own. For some polio sufferers with permanent damage to their lungs, they became an essential part of their existence.

As fewer and fewer people used them, the companies who produced them urged people to use alternative breathing aids. In 2004, one of those corporations, Philips Respironics, told iron lung users they could no longer guarantee they would repair the machines.

Mr Alexander said he was keen to visit Britain (Nick Isenberg/YouTube)

In 2013, the Post-Polio Health International, an organisation which works to help polio sufferers, estimated there were six to eight iron lung users in the United States.

Asked how many there were today, the group’s president, Brian Tiburzi, said: “I don’t have an answer to that. I don’t think anyone knows for certain.”

Gizmodo spoke to three people who still use the machines - Mr Alexander, 70, of Dallas, Martha Lillard, 69, from Oklahoma, and 81-year-old Mona Randolph of Kansas City, Missouri. They may be the very last individuals to rely on this outdated machinery

Mr Alexander, who contracted polio in 1952 when he was six, said he spent nearly every moment in his iron lung, located in the centre of his living room. He answers the phone and types using a plastic wand attached to his mouth.

Remarkably, despite his dependence on the machine, he went to law school and worked as a lawyer.

National Polio Immunisation Day in New Delhi, India

“When I transferred to the 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,” he told the website.

“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.”

Mr Alexander has frequently had problems with maintaining his machine and in 2015 a friend put a video of him on YouTube that explained his problems and of his search for someone who knew their way around an iron lung machine.

Eventually, Brady Richards, who runs the Environmental Testing Laboratory, a Texas-based firm which tests equipment to ensure it meets environmental standards, got in touch.

“I looked for years to find someone who knew how to work on iron lungs,” said Mr Alexander. “Brady Richards, it’s a miracle that I found him.”

Polio: iron lungs, leg braces and vaccination Show all 8 1 /8 Polio: iron lungs, leg braces and vaccination Polio: iron lungs, leg braces and vaccination A hospitalised child suffering from polio shows off his biceps to a doctor in 1947 Getty Images Polio: iron lungs, leg braces and vaccination Children being given an oral vaccine for polio, known then as infantile paralysis, in Hull during the 1961 epidemic Rex Features Polio: iron lungs, leg braces and vaccination A boy suffering from polio being treated with a type of 'iron lung' in hospital. A nurse operates the equipment at the end of the bed which controls the flow of air pressure Getty Images Polio: iron lungs, leg braces and vaccination A woman sees her new born baby whilst lying inside an iron lung as part of her treatment for Polio Getty Images Polio: iron lungs, leg braces and vaccination Polio victim Margaret Dixon watching the opening matches of the 1957 Wimbledon championships from her invalid chair Rex Features Polio: iron lungs, leg braces and vaccination Young children polio patients doing physiotherapy exercises wearing calipers against their outside beds at Wingfield Nuffield Orthopaedic hospital in Oxfordshire Rex Features Polio: iron lungs, leg braces and vaccination A five year old polio victim walks into the outstretched arms of Doctor George Deaver, faculty member of the New York University College of Medicine, during a demonstration at the Institute of Rehabilitation and Physical Medicine Getty Images Polio: iron lungs, leg braces and vaccination 6 May 1956: First injections for children against polio at the Hendon clinic Getty Images

Mr Richards said he visited Mr Alexander once every six months. “The machine is actually the most simple thing on the planet,” he told The Independent. “The problem is that they no longer make the parts.”

Ms Lillard said she was infected with polio when she was five. Now, she spends half of every day in the machine.

“All the mothers were just terrified because people were just getting it right and left,” she told Gizmodo of her infection. “They didn’t know if it was a virus or bacteria or how you caught it.”

Ms Randolph became infected when she was 20. She said she tells children who ask what happened to her that she was damaged by a virus because a vaccine was not available.

She said she was deeply upset when she met anti-vaccine activists.