Utah health officials on Monday were reviewing 21 cases of severe vaping-related illnesses, about a week after the U.S. Centers for Disease Control warned of a cluster of lung disease cases that appear to be linked to e-cigarettes.

The updated number more than doubles the 10 cases the Utah Department of Health had learned of statewide as of last week.

Health officials also are investigating another five unconfirmed cases, department spokeswoman Rebecca Ward said.

Across the country, health officials are looking into an outbreak of severe lung disease that appears to be tied to vaping; the CDC was investigating nearly 200 cases nationwide as of last week, and doctors attributed one death in Illinois to vaping.

Before experiencing respiratory distress, patients have reported initially mild symptoms such as shortness of breath and chest pain; many also have experienced gastrointestinal problems, including nausea and diarrhea, the CDC reported.

Doctors in Utah have encountered multiple cases of lipoid pneumonia in vaping patients, where fat deposits, possibly from oil in vaping juice, have been found in microscopic air sacs in the lungs.

The state health department is collecting samples of vaping juice from affected patients to test the contents, Ward said. Patients were vaping nicotine in some of the cases, THC in others — and in some cases, both. Doctors do not yet know what ingredient may be causing the illnesses.

“The department ... is conducting testing on vaping products to determine if the products contain inhalational drugs, for example, nicotine, THC or any other harmful substances that may contribute to severe lung illness,” Ward said.