(WESH) – The Centers for Disease Control and Prevention has identified the first U.S. cases of a drug-resistant fungal infection.

The CDC said Friday that 13 people have become ill from Candida Auris, a sometimes fatal infection with a high likelihood of causing outbreaks in healthcare facilities.

The deadly organism is difficult to identify using traditional laboratory methods.

Seven U.S. cases occurred between May 2013 and Aug. 2016 in Illinois, Maryland, New York and New Jersey. Four of the 7 infected patients died, but it is not yet clear if their deaths were due to C. Auris, officials said.

Lab evidence suggests these cases are related to those in South America and South Asia with transmission occurring in healthcare settings.

The CDC director called the fungus an emerging threat, saying “we need to act now.” The CDC said it is reminding health care facilities to strictly follow cleaning procedures.