A drug-resistant superbug fungus has sickened nearly 600 people across the United States in recent years, including more than 300 patients in New York State, the Centers for Disease Control and Prevention reported. Candida auris, which preys on people with weakened immune systems, can be deadly.

CBS New York reports an elderly man died from the fungus last year at Mount Sinai Hospital following abdominal surgery.

“Most C. auris cases in the United States have been detected in the New York City area, New Jersey, and the Chicago area,” the CDC said in a statement.

The fungus was seen in the U.S. for the first time in 2013. Dr. Lynn Sosa, Connecticut’s deputy state epidemiologist, told The New York Times that she views she views Candida auris as “pretty much unbeatable and difficult to identify.”

As of the end of February, a total of 587 cases had been confirmed across the country, most of them in New York State, where there were 309 cases. Illinois had 144 confirmed cases and New Jersey had 104.

Symptoms of Candida auris

According to the CDC, symptoms of the fungus may be difficult to detect because patients are often already sick and only a lab test can identify the superbug. Candida auris can cause different types of infections, including bloodstream infection, wound infection, and ear infection.

People who recently had surgery, live in nursing homes, or who have breathing tubes, feeding tubes or central venous catheters appear to be at highest risk.

“Based on information from a limited number of patients, 30 – 60% of people with C. auris infections have died. However, many of these people had other serious illnesses that also increased their risk of death,” the CDC said.

Treating Candida auris

While most Candida auris infections are treatable with antifungal medications, the CDC says it’s concerned that some have proven to be resistant to all three main classes of antifungal medications. “In this situation, multiple antifungal medications at high doses may be needed to treat the infection,” the CDC said.