The conditions he works in are stark. Nobody has running water. There is no power grid. The hospital does feature a simple solar power grid with a backup generator, a steam sterilizer and one flush toilet. "It's a very basic, basic world," Dr. Catena said.

That world is also caught between armed factions in a brutal civil war, dealing with famine, disease and no help from the government. "The government is trying to exterminate us, not help us," he said. "We get no government assistance."

Yet he carries on, determined to serve the people counting on him and Mother of Mercy Hospital for medical treatment. "They travel for a week to come to the hospital, and they don't think a thing about it. I see them for five minutes and then they go home," Dr. Catena said. "The people are tough. They are resilient. People there are hard as nails."

Often, though, they turn to the local shaman first for their medical needs. Dr. Catena recounted a case where a woman broke her leg and went to the shaman for help. The shaman put the leg in a splint and wrapped it so tight with tree bark that it cut off circulation. She finally came to him because her leg was getting worse.

"The only thing we could do was amputate," he said. "This is quackery — very dangerous. We've had to amputate a bunch of people because of this guy."

It's frustrating, he said, and very difficult to overcome. So he turns to God. "Without that Christian hope ... there is no way I could make it," he said. 

"Our situation now is terrible. We have civil war, famine and a cholera outbreak." The emotional toll is constant. "Have I felt like I'm at the end of my rope? That comes about five or 10 times a day. We see the value of what we do, and that keeps us going. We have tragedies that just tear your heart apart every day. Sometimes we have bad outcomes. It's a very heavy burden to carry," Dr. Catena said. "If I take that feeling of that first person ... I wouldn't be ready for those other patients."

During his presentation, he challenged the students of the Edward Via College of Osteopathic Medicine (VCOM) with several raw cases, seeing if they could diagnose them: melanoma, syphilis, lupus, tumors, leprosy, even bladder stones. He learned to diagnose them first at Duke University School of Medicine, then on the job at a hospital in Kenya.

Dr. Catena said he got into medicine after pursuing a mechanical engineering degree at Brown University. "I wanted to do missionary work," he told the students. "I thought medicine was a better fit." He wanted to serve God as a missionary in a place with the greatest need.

"I was younger then, tons of energy. Why did I go to Sudan? That's where the greatest need is. I wanted a challenge," he said.

So he focused on medicine, spending seven years in Kenya learning how to diagnose and operate. "A lot of stuff that we do isn't stuff that you will do here," he told the students. "I had very good doctors that were willing to teach me stuff. I learned a ton from these guys."

Especially one Kenyan surgeon. "He was a wizard. He was very patient with me," Dr. Catena said. "I had excellent mentors."

After doing 1,000 operations, Dr. Catena said he was ready for Sudan, where he had contacted the local bishop, who was building Mother of Mercy Hospital. "I felt very comfortable," he said of his start in Sudan in 2008. "I was looking for that kind of challenge. I think I got it."

Part of that challenge included finding people to help in the hospital. That was tough because the education system was lacking. He was looking for people who could just read and write, and he put them to work, teaching them what they needed to know. One was in sixth grade; another was in eighth grade. But they have learned and have come a long way.

In 2012, Mother of Mercy Hospital partnered with African Mission Healthcare, which now serves 32 hospitals in 11 countries. The organization helped Dr. Catena carry the financial load and assisted in training nurses, internists and other staff critical to the operation of a hospital.

Now they are traveling with Dr. Catena across the United States, raising funds for his hospital.

"Their annual budget will be about $3 million this year," according to Scott Marcello, president of African Mission Healthcare. So far, the fundraising tour with Dr. Catena has raised $1.5 million, Marcello said.

In the Upstate, Dr. Catena stopped at Christ on Main, VCOM, University of South Carolina School of Medicine in Greenville and St. Mary Church. Next he will head to Kernersville, North Carolina, then west, before coming back east, stopping at Notre Dame and finishing up in New York.

"We want to raise $4 million on this tour," Marcello said.

That will ease Mother of Mercy's burden. So will Marcello's bid to develop medical staff. 

"We also train nurse anesthetists and medical officers," Marcello said of African Mission Healthcare. "We're also hoping to train some surgeons."

Marcello told the crowd at St. Mary that the partnership is focused on making "Tom's hospital ... stronger, better and more effective." Dr. Catena reminded the St. Mary crowd of his start in the Nuba Mountains, pointing to a girl in the crowd and saying, "That sixth grader, she'd be our head nurse. That was the reality of starting there."

Mother of Mercy Hospital has come a long way since Dr. Catena showed up in 2008. "We've traveled a lot of miles," he said, and he is building for the future. "We expect Tom's hospital to take care of 300,000 patients next year," Marcello said. "He'll do 3,000 surgeries. Tom is the only surgeon for this group of 3 million people."

Help might be coming from South Carolina. Matthew Cannon, dean of VCOM, brought three of his students to Dr. Catena to talk about missionary work. Elle Solerberg said she has already been to Kenya after contacting Samaritan's Purse, and she wants to go back to Africa. Alyssa Blackwell and Elena Kiselev also want to help out somewhere in the continent.

"We talked about culture and faith and how that pushes him," Blackwell said of Dr. Catena. "He needs all kinds of specialties," Kiselev said. "Training up. That is a huge part," and the three VCOM students added that they are trusting the Lord to lead them.

Cannon was proud to have Dr. Catena discuss medicine with his VCOM students. "He is the epitome of selfless service," Cannon said of Dr. Catena. "He is an inspiration and a motivation. He gives them an opportunity to see what they can do. He has proven that you can do what you set your mind to do."

It starts with a staunch faith, a willingness to follow God and to serve.