SALT LAKE CITY — University of Utah doctors said Friday they are continuing to work to get to the bottom of a vaping-related illness affecting dozens of youth in the state and hundreds around the country.

As of last report, 35 people in Utah have been affected by the illness that causes shortness of breath, fatigue, chest pain and coughs. All patients reported vaping nicotine, THC or both.

“I think it’s fair to call it early phases of an epidemic. This is something that has really spiked since this summer, so it’s pretty new,” said Dr. Cheryl Pirozzi, assistant professor of pulmonary and critical care medicine at the University of Utah Hospital.

No single vaping device has been tied to all of the cases, she said.

The U. hospital has seen 13 confirmed cases, with several more suspected cases awaiting confirmation.

“And they are still coming in,” Pirozzi said. “The majority of our patients are young, previously healthy people who are coming in with shortness of breath.”

The U. discovery announced last week of lipid-laden macrophages — fatty oils found in the lungs of those with the illness at the hospital — might help doctors determine a cause and treatment, she said.

“Whether this is a driver of disease or just a marker, a representation of the disease itself, either way, this has been helpful for us for identifying patients. And as we share this knowledge across the country, it’s been helpful for other physicians to help identify this disease,” said Dr. Sean Callahan, assistant professor of pulmonary and critical care medicine.

Meanwhile, national health officials have reduced the number of confirmed cases from more than 450 to 380 after developing a new definition for the illness that excludes those whose cases were under investigation, and those who had an infection not tied to vaping or e-cigarette use.

Six deaths have been confirmed in six different states — California, Illinois, Indiana, Kansas, Minnesota and Oregon, according to the Centers for Disease Control and Prevention.

Health officials have called for people to stop vaping while the illness is investigated. Sen. Mitt Romney, R-Utah, on Tuesday called for the Food and Drug Administration to recall e-cigarettes.

The Drug Safe Utah Education coalition is also urging the Utah Legislature to ban vaping for people under age 21, citing the “overwhelming dangers involved with vaping and evidence of THC causing respiratory disease.”

The coalition wants legislators to implement the ban on Monday when it meets during a special session to change the state’s medical cannabis law, which as currently written allows people to vape THC.

The group purchased a full-page ad in Sunday’s Deseret News calling on the Legislature and Gov. Gary Herbert to take action to protect children from the “vaping crisis.”

Some, meanwhile, have argued that the illness has likely been caused by black market or counterfeit products.

The U. patients used “a variety of products, many of which, I think, are regular, store-bought products,” Pirozzi said.

“I don’t know if this is what the underlying cause of this is, but I caution people to understand that often these are young people that can’t distinguish the difference between the black market versus the real product. So that’s why the safest thing is just don’t vape right now,” Callahan said.