Rabbi Henry Jay Karp has one healthy lung, like Pope Francis. (Courtesy Rabbi Henry Jay Karp)

Pope Francis' legion of new admirers includes a perhaps unlikely figure: a rabbi living along the Mississippi River.

Like the new world leader, Rabbi Henry Jay Karp has just one healthy lung.

"There's a kinship, because when you lose basically the use of one lung, it does change your life perspective to a certain degree," said Karp, 63, a Bronx native who has presided over the Temple Emanuel synagogue in Davenport, Iowa, for nearly three decades.

Losing major lung capacity can do one of two things, he said. It can lead you to fold into yourself and look at all the things you can't do and be afraid to do things. Or it can present you with a challenge.

In the case of Pope Francis, 76 - formerly known as Cardinal Jorge Bergoglio, whose lung was reportedly removed when he was a teenager after an infection - the path he chose is unmistakable, he said.

"One lung or two lungs, it's very clear that Pope Francis has led a life of speaking out, speaking out for the poor, for those in need and for justice," Karp, who writes a blog called "Reflections of an Iowa Rabbi," told ABCNews.com. "He has a good deal of breath to carry the message of justice forward, and that's inspiring."

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Karp was diagnosed as having a dysfunctional diaphragm in 2010 after he started getting short of breath, he said. At first he thought the cause was his asthma. After a summer of tests, though, doctors realized a virus had destroyed the nerve to his left diaphragm.

Surgeons at the Mayo Clinic in Minnesota "sewed down" his diaphragm to make room for his left lung to be reinflated, and now his left lung is functioning but at a very low level, he said. Karp works with a trainer twice a week to help develop surrounding muscles so he can make the most of his healthy lung, he said.

Doctors may have removed the lung of the Vatican's new leader for a number of reasons: tuberculosis, whooping cough, complications from pneumonia, or because of a congenital lung defect the pope may have been born with that later caused an infection, Dr. William Schaffner, chairman of preventive medicine at Vanderbilt University Medical Center in Nashville, Tenn., told ABCNews.com yesterday.

In terms of daily life, Karp said he gets breathless when he carries around the Torah during services. He can't walk fast, which can affect travel plans.

"When you fly out of a place like Iowa, there are few direct flights," he said. "I don't take tight connections so I can get to the gate and still breathe," he said.

Living with one lung doesn't usually affect people's daily life or life expectancy, said Dr. Len Horovitz, an attending physician in internal and pulmonary medicine at Lenox Hill Hospital.

Just look at the new pope.

"He's been living with one lung for 60 years," Horovitz told ABCNews.com. "He's already gotten pretty much to the life expectancy of an American man."

Doctors have been performing pneumonectomies - removing lungs - for about that long, or 70 years, he said. Afterward the healthy lung normally expands somewhat, he said.

A missing lung really only affects a sufferer's ability to exercise, yet even running a marathon technically wouldn't hurt the existing lung, he said.

The links between Karp and Pope Francis don't stop at lung issues or even being a member of the clergy. Karp teaches theology at Saint Ambrose University in Davenport, a Catholic school.

Recently he worried about taking students on a major field trip to Eastern Europe, he said. He managed to overcome his fear, however, he said.

He recalled thinking, "I can't do this trip. How am I going to be able to schlep around concentration camps?" he said. "But I said, 'No, I'll pace myself. And I did that trip."