SASKATOON -- Scientists at the University of Saskatchewan say they think they've discovered why people with cystic fibrosis are prone to lung infections.

The 18 researchers say they've concluded that the genetic mutation that causes cystic fibrosis prevents normal secretion of airway surface liquid, including mucus.

"Airway surface liquid is crucial to kill bacteria because airway surface liquid has anti-microbial properties and is sticky to bacteria, so bacteria gets stuck to it," said lead researcher Juan Ianowski Thursday.

Little hairs called cilia then push the germs out of the airway.

Ianowski, an associate professor in the physiology department at the University of Saskatchewan, and his team developed a technique to look inside the airways of normal pigs and piglets modified to have cystic fibrosis, but in the earliest stage of the disease.

He says there has long been interest in that "window at the very beginning of life where everything's still quite healthy." The question was, what exactly caused a healthy lung to become a sick one?

"If one were able to identify what that thing is and could stop it, one would wonder if you could stop the disease," he said.

"The inability to kill bacteria has been identified for a long time as a problem, but it was never terribly clear why that was the case."

One theory developed many years ago was that airway surface liquid production is abnormal, but there was no way to prove it.

But technology improved. Ianowski says it took seven years to develop the technique needed to see the production of mucus in a living animal -- a liquid so thin, it's about the width of a hair.

The researchers found that the piglets with cystic fibrosis never produced the normal amount of airway surface liquid in their lungs to fight off bacteria, "which means the bacteria will be more likely to remain, to reproduce and to cause infection," said Ianowski.

Eventually, he said there's permanent lung damage from chronic infections.

Cystic Fibrosis Canada, which partly funded the research, estimates that one in every 3,600 children born in Canada has the disease. The organization says it is the most common fatal genetic disease affecting Canadian children and young adults.

But the findings, reported in the journal Nature Communications, do not mean a cure is imminent and more testing is needed, cautioned Ianowski.

"We are far from a treatment," he said. "This paper does not give us data supporting any particular treatment. This paper indicates that, if it is correct, if we were able to ... increase the amount of liquid at the very, very beginning, we might have an improvement on the prognosis of the disease."

-- By Jennifer Graham in Regina