The number of Utahns suffering from severe lung disease associated with vaping has jumped to 35, according to the Utah Department of Health.

Another 12 potential cases are being investigated, the department said in a news release.

Nationally, there have been more than 450 cases in 33 states, and five deaths — in California, Illinois, Indiana, Minnesota and Oregon — have been linked to vaping.

The outbreak has mystified health officials nationwide as to how vaping is physiologically causing the illnesses, and why cases are just now clustering even though people have vaped for years.

But researchers in Utah say they have taken the first steps to confirm a possible link between traces of a fatty substance in the lungs, associated with vaping, and the illnesses.

Doctors at the University of Utah, where 12 patients have sought treatment for vaping-related illnesses, flushed out each patient’s lungs to identify abnormalities. In each patient, the procedure flushed out cells, called macrophages, which are part of the immune system. The cells consume and destroy microscopic particles of foreign matter.

Macrophages are normally present in people’s lungs, said Dr. Scott Aberegg, a critical care pulmonologist at University Health. But in each of the 12 patients suffering from vaping-related illness, the macrophages were “lipid laden” — that is, particles of fat or oil were clinging to the cells.

“While it is too soon to be sure, these lipid-laden macrophages may turn out to be useful to confirm or rule out this disease,” said Aberegg, who published the findings on Friday in the New England Journal of Medicine.

The next step, he said, is to design a study of people who vape but have not fallen ill, to determine whether the particles of oil are associated with vaping-related illness, or simply are a result of vaping in general.

The researchers at the U. still don’t know how the oily droplets may be causing patients to become so severely ill — some in Utah have nearly died — or what component of the inhaled vapor is bringing the oil into the lungs. Most of the University of Utah patients have vaped THC products, Aberegg, but statewide and nationwide, investigators have found that patients who vape nicotine also became ill.

Among Aberegg’s patients, vape juices bought on the street or made at home appear to be common, he said, as opposed to commercially bought cartridges — though he said at least one of his patients became ill after vaping a THC product purchased in a store out of state.

But, Aberegg added, “No one should vape until we understand the cause of these illnesses.”

Utah’s investigation is consistent with reports by the Centers for Disease Control and Prevention and the Food and Drug Administration that “there is no consistent brand or product associated with these illnesses.” State health officials reported that they have tested several THC cartridges that contained “significant amounts of vitamin E acetate,” but that there is “insufficient evidence to conclude THC or vitamin E acetate are the cause” of the lung injuries.

Now the state has formed a task force with doctors from multiple health systems to study cases as they are reported, said Dr. Dixie Harris, a pulmonology and critical care specialist with Intermountain Healthcare.

Harris was among the first doctors in Utah to report a possible connection between vaping and a spate of serious illnesses. Patients were complaining of cough, shortness of breath, chest pain, fatigue and, in most cases, gastrointestinal problems like nausea, vomiting and diarrhea. In Utah, 94% of patients have required hospitalization, according to state officials; some have required ventilators to help them breathe.

It is possible, Aberegg said, vaping-related illnesses previously occurred but were mistaken for viruses or pneumonia, the patients recovered, and doctors did not know the symptoms were tied to vaping.

In the first weeks of the outbreak, Aberegg said, University of Utah doctors identified about six patients believed to have developed vaping-related illnesses. But last week alone, he said, seven more patients appeared.

Of the more than 20 patients reported by Intermountain, Harris said, “all of them have stopped vaping, which is amazing.”

The health department continues to urge caution when using vaping products and to avoid vaping THC oil concentrate cartridges; avoid buying products off the street; and avoid modifying or adding substances to vaping products.

"Youth should not be using any vaping product,” state health officials warned.