Two hours a day, Jeff Davis works at staying alive. He inhales a succession of medications, runs on a treadmill and sometimes performs breathing exercises that produce gurgly, crackling sounds.
It is tedious work, crammed into a life that includes a full-time job as a machinist and leisure time with his wife and two children. But it has paid dividends: A generation ago, few people with cystic fibrosis lived past their teens — Davis is 35.
Davis's case is typical, having soldiered through childhood with a closet full of medications and parents who spent hours thumping his torso to keep his lungs clear.
“They told my parents that if I lived to be a teenager, that would be about it,'' Davis said during a recent visit to Johns Hopkins Hospital's adult cystic fibrosis clinic in Baltimore. “The fact they even have an adult clinic is amazing.''
Affecting 30,000 people in the United States alone, cystic fibrosis is an inherited disease that causes the body to produce thick, sticky mucus that can clog the lungs and damage the pancreas, interfering with the body's ability to absorb nutrients. As a result, victims are prone to respiratory infections and struggle to gain weight.
In the early 1960s, the median survival age was 10. Desperate parents watched children cough their way through life and succumb to infections, even malnutrition.
But a steady progression of drugs, medical devices and improvements in disease management has made it possible for patients to not only survive longer but also attend college, have careers and raise families. By the early 1980s, median survival had risen to 21 years. Today it is 37.
“We now expect children to live into adulthood and to be healthy as well,'' said Dr Peter Mogaysal, director of the cystic fibrosis centre at the Johns Hopkins Children's Centre. “Several decades ago, most people with CF died in childhood and it was the exception to have patients live to be an older adult.''
To achieve that, patients face steep challenges — not just lung infections and the likelihood that they will die of the disease but daily treatments that can sideline them from things they would rather be doing.
“We're talking about the late-teens, a time when all of us are trying to get careers, find spouses and think about having a family,'' said Dr Michael Boyle, who runs the adult clinic at Hopkins. “They're doing all those things — plus spending an hour or two maintaining their health.''
Until the 1990s, there weren't enough adult survivors to justify a clinic of their own. Since the clinic's founding, the caseload has grown from 40 patients to 200.
Whatever their symptoms, patients suffer from a single underlying problem.
By inheriting a mutant gene from each parent, they are saddled with a defective protein that sits on the surface of cells lining the lungs, airways and pancreas.
The protein is supposed to maintain a proper balance of salt and water, inside and outside the cells. Instead, the salt concentrates in the cells, and the mucus lining the airways becomes thick and sticky — the bane of a patient's life.
Over the years, scientists have chipped away at the disease through improvements in therapies. There are better antibiotics to prevent and treat infections and new drugs to thin out the mucus. There are also enzymes to compensate for chemicals the pancreas should make but can't.
Doctors push medications more aggressively than before and encourage patients to eat all the steak and dairy products they want. “Studies found that patients who eat higher levels of fat and more calories were actually living years longer,'' Boyle said.
But therapies treat symptoms, not the defect that triggers them. So patients generally still see their lung function decline over time. The disease eventually overwhelms them and they die when their lungs cannot deliver enough oxygen to the bloodstream.
At Hopkins and other speciality centres, doctors are testing a group of medications designed to make the protein work correctly. Any one of them could represent the quantum leap was so far elusive.
“These are interesting and good times to be in cystic fibrosis research,'' said Dr Craig Gerard, who treats patients at Boston Children's Hospital. “We now have drugs in development that directly target the nature of the disease.''
Meanwhile, patients are reaching milestones never before thought possible.
James Albright, 44, runs an International Baccalaureate programme at a middle school in Northern Virginia. There, students barely take notice of an intravenous tube carrying medications into his arm.
When they married nearly 20 years ago, Albright and his wife faced an uncertain future. “I was pretty up-front about it,'' he said. “If we could get five good years out of it, it would be great. I couldn't promise anything beyond that. But married couples tend to live longer — my goal is seventies.''
The couple adopted three boys, including one with cystic fibrosis. Men who have the disease are born with a natural vasectomy, lacking the duct that carries sperm from the testes, but they can conceive with reproductive assistance.
Female patients can also conceive — but they must consider whether they can endure the rigours of pregnancy. And, like adult males with the disease, they must consider how long they will be around for the children.
“The question is whether it's right for you,'' Boyle said. “It's a hard question to ask of someone who is 28 years old and trying to live a normal life. We try to be supportive but help them be realistic.''
Jeff Davis and his wife, Kim, had two in vitro babies. Kim had genetic tests that determined she wasn't a carrier, so there was no chance the children would be afflicted.
They live in a split-level that overlooks a landscape of rolling hills. Life at home seems relaxed, despite the lingering knowledge that his health is not assured.
“Is it going to be a couple of years, or 20 years? Am I going to be there in their teenage years when they need me? Am I going to be there to guide them? You have to take it all into consideration, but you can't let it rule your life,'' Davis said.