The cases are all tied to former nurse Elet Nielson, who was accused of stealing drugs from both Davis and McKay Dee Hospitals from 2011-2013.
The first cases popped up a couple of years ago and started an investigation that now has uncovered more than a dozen infected patients.
With 16 confirmed cases, there is still concern that nearly half of the 7,217 people who may have been exposed have not come in for free testing.
Hepatitis C is treatable, but can cause death if left undiagnosed and untreated.
"We do know in the U.S., the most common way of transmit Hepatitis C is through needles and the only way to transmit Hepatitis C is blood to blood," Dr. Angela Dunn, a CDC epidemiologist, said. The cases were transferred through blood in a hospital setting but "unfortunately we do not know how it happened," she explained.
The assumption is that Nielson, 49, who was working as an emergency room nurse was sharing needles for IV drugs with patients.
Nielson's record of troubles started at Davis Hospital where she was let go for stealing Benadryl in 2013. She started nursing at McKay Dee hospital not long after, where her alleged thefts escalated to narcotic IV drugs that disappeared on a weekly basis.
"Unfortunately I do not have a way of 100 percent knowing how the virus is transmitted and the directionality of the virus," Dunn said, adding that Nielson could have contracted Hepatitis C from a patient and then passed it to others, or could have been the original carrier.
Hepatitis C 2B is it a pretty rare genotype. It is only 8 to 10 percent of all hepatitis C in Utah, therefore making it easy to pinpoint connected cases.
So far, 3,731 people have been tested, but just as many still have not.
The investigation found 53 Hepatitis C cases, but only 16 are linked to the nurse so far. One is from Davis hospital; the rest from patients of McKay Dee hospital in Weber County.
"Outrage, just pure outrage," said Aime Schofield, whose son was possibly exposed to the virus. "They definitely broke my trust. I don't want to go back there, if they let this woman in there for so long and didn't catch it. What if there's another nurse?"
Trust issues could be keeping nearly 4,000 possibly exposed patients from being tested.
"The good news" according to Dunn "is there is treatment for most cases of Hepatitis C and the hospitals are working closely with the patients to get that done."