A deadly “superbug” fungus that is hard to spot and harder to kill is slowly infiltrating U.S. hospitals, health experts say.

Candida auris enters the bloodstream, spreads throughout the body and causes a variety of infections, the Centers for Disease Control and Prevention warns. More than 60 cases have been identified in the U.S., all but a few of them in New York and New Jersey. The CDC has alerted hospitals and other health care facilities across the nation to watch out for the relatively new fungus.

The fungus can be passed between people or through the environment from such things as hospital equipment, says Dr. Tom Chiller, chief of the CDC’s Mycotic (fungal) Diseases Branch.

Some strands of the fungus found in other countries have been resistant to the three classes of anti-fungal medicine, he said.

“We are dealing with an organism we don’t have drugs to treat. That is what worries us,” Chiller told USA TODAY. “What we have seen (in the U.S. so far) has been treatable. We are trying to aggressively contain it, stop it and kill it.”

The CDC says patients in the intensive care unit for a long time and patients who have a catheter placed in a large vein appear to be among those facing the highest risk of infection. The fungus has caused bloodstream, wound and ear infections. It also has been found in respiratory and urine specimens, but it is unclear if it causes lung or bladder infections.

The CDC issued a report six months ago saying the fungus had been found in 13 people and was linked to four hospital patient deaths in the U.S.

Candida auris can kill and is probably is killing,” Chiller says. “We are seeing a 30% death rate, but these are often very sick people with a lot of medical problems when they get it. It’s hard to determine how much of (the death toll) is really related to the fungus.”