A Las Vegas hospital is experiencing a tuberculosis outbreak, according to a report released by the Southern Nevada Health District.

The findings show that out of the 977 people tested at Summerlin Hospital Medical Center, 59 individuals tested positive for latent TB infection – where patients do not show symptoms and are not contagious. Two individuals were diagnosed with active disease, Fox 5 reports.

Health officials point to an infected mother who gave birth to premature twins in May as the potential origin. An earlier report found the hospital failed to diagnose the 25-year-old mother, Vanessa White, with the infectious lung disease.

White, who was sick both before and during her pregnancy, continued to visit her children in the hospital after she was discharged. She was later transferred to a Los Angeles hospital before she died. An autopsy revealed she had tuberculosis. Both twins, Emma and Abigail, remained in Summerlin Hospital Medical Center’s Neonatal Intensive Care Unit and later died of tuberculosis, the Las Vegas Sun reports.

The health district says 142 infants needed evaluation for exposure and that many of those tests remain incomplete – meaning the infant  did not have a tuberculin skin test (TST), chest x-ray, or physical exam documented, for up to three rounds of testing.

"We want physicians to really think about making the diagnosis and quarantining, and then calling us," Dr. Joe Iser, chief medical officer at the health district, told the Associated Press. "This has been very expensive for us in terms of time and effort and dollars."

TB is spread through the air from one person to another – this can be from coughing, sneezing, speaking or singing. Not everyone infected becomes sick. A latent TB infection can live in a person’s body without being contagious or show any symptoms. If the TB bacterium becomes active and multiplies, it can turn into TB disease. Those with the active infection may have chest pain, a bad cough that lasts for at least three weeks and cough up blood or sputum. If left untreated, TB can be fatal.

While the number of TB cases in the U.S. reached its lowest point in 2012, the latest outbreak shows the disease can still resurface if proper precautions are not followed.

An earlier report found 26 people, including White’s family members and other hospital workers were infected with TB. In November, eight employees, former patients and visitors filed a lawsuit claiming the hospital was negligent and is seeking damages, the Associated Press reports.

Health officials say they plan on testing infants treated at the hospital in the next few months to make sure they do not show signs of disease.