US-based disaster response nurse fighting coronavirus in Italy: 'I've never ... left a disaster to go to another disaster' The Michigan native has treated patients in disaster zones for 10 years.

Kelly Sites, a registered nurse from Michigan, has been treating patients around the world for 10 years as part of a disaster response program. This year, she’s been fighting the novel coronavirus at a field hospital in Italy.

“I usually leave home to go to a disaster," Sites, who's currently working on her 19th deployment to a disaster relief area, told "Nightline." "I've never left a disaster to go to a disaster."

Out of the 600 beds at the Cremona hospital, 500 are being used for COVID-19 patients, Sites said, adding that she and her team have moved to the parking lot to make use of the extra space for beds.

“We are very short on the PPE, the personal protection equipment. The masks are hard to find… We have gowns that we have to wear, gloves. All of those items worldwide are a shortage,” she said.

Sites said that 100 of the hospital's 500 medical staff have now tested positive for COVID-19. She said it's caused a new range of problems for the hospital.

“They’re frontline workers and they’re in the trenches taking care of patients,” she said. “They had a lot of medical staff who are out because they are sick, so [others are] working overtime. They have many other physicians, like orthopedic surgeons, who are now working as pulmonologists with ventilators, so it's a challenging situation for them.”

Sites said fighting COVID-19 in Italy has caused emotions to reemerge from her time battling Ebola in Liberia.

“I was there at the beginning of the outbreak in Liberia and then I was there at the peak of the outbreak in Liberia, and I felt how I feel now. When there was no treatment and there wasn't anything we could do but offer supportive care, that's how I feel,” she said.

“There is no known treatment for COVID[-19],” she added. “There is so much unknown about it but we’re here to do it, we’ll see what happens and I believe that we’re ... really going to save some lives here."

Sites said she hasn’t been keeping up with the skyrocketing numbers of novel coronavirus cases and deaths in Italy.

“Honestly we are working so hard that I have lost touch with what’s even going on with that,” she said. “I know its staggering… It's staggering and it continues to rise.”

So far, Sites said her team hasn’t been forced to decide which patients to save. "Not yet," she said.

“It’s hard to know what’s coming ... in the future, but we’re doing everything we can to help and support patients. So far, we’ve been doing well,” she said.

Sites said she believes her home country is just a few weeks behind where Italy is today.

“It didn't take long to get here, where we’re at today, and it rapidly escalates,” she said.

She shared a message for the U.S.: “Social distancing is not a hype and a panic thing. It’s a strategy… This is a shift in mindset, we need to shift our mindset to not just think about ourselves and our personal safety but [how] what we do radically helps others.”

Ultimately, she hopes the world “will pay close attention and have a little more … compassion,” she said.

“Let’s fight this thing together," she said. "You know, we’re all in this together. Literally.”