WOODLAND PARK, N.J. – At least 587 cases have been confirmed over the last few years of an emerging fungus infection, identified by U.S. health authorities as "a serious global health threat."

Centered primarily in the New York City area, the Chicago area and New Jersey, Candida auris infections had spread to a dozen states by the end of February, the U.S. Centers for Disease Control and Prevention reported.

The fungus – also referred to as C. auris – is resistant to some or all antifungal medicines, which makes it harder to treat, the CDC says.

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Found in hospitals and long-term care facilities, it can quickly lead to death in patients who have weakened immune systems or other underlying serious medical problems. More than one in three patients with an invasive infection of the fungus has died, the CDC said.

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Of the 587 cases nationwide that the CDC confirmed citing February data, New York had 309, more than any other state. Illinois had confirmed 144 cases, the agency said.

New Jersey health officials reported Tuesday that over the last four years the state has 132 confirmed cases and another 22 that are considered probable.

"It's taken us all by surprise," said David S. Perlin, the chief scientific officer of the new Hackensack Meridian Health Center for Discovery and Innovation, in Nutley, New Jersey.

As former head of the Public Health Research Institute in Newark, Perlin published several studies in the last two years about diagnosing drug-resistant fungal infections, including C. auris.

"We don’t really know why globally this bug has burst on the scene all over the world." he said. "We're seeing it in hospitals – we have a problem obviously in New York and New Jersey, but we see it in Spain, the United Kingdom, South Africa, other places."

C. auris spreads in hospitals and health care settings via surfaces, where it persists for days, and from person to person, he said. Those modes of transmission – and its persistence – are extremely unusual for fungal diseases.

What makes C. auris so deadly is that it is difficult to treat and often misidentified, the CDC says. Unlike bacterial infections, for which doctors have many antibiotics, fungal infections are treated by three main classes of drugs. However, some of the C. auris infections are resistant to all three.

Patients who have been hospitalized for long periods, those with a central venous catheter or other lines or tubes into their body or have previously taken antibiotics or antifungal medications are the most vulnerable to the fungus.

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C. auris was first identified in 2009 in an ear infection in a Japanese woman, but the earliest known strain dates back to 1996 in South Korea, according to the New Jersey Department of Health. Since then, it has spread to at least 20 other countries.

The CDC alerted doctors in June 2016, asking them to report cases. Two months later, the first seven cases in the United States were reported, six of them dating from before the CDC's notification.

An additional 1,056 patients have been "colonized" with the fungus, but did not show symptoms, the CDC said. They were identified through screenings in seven states where patients had become sick with the fungal infection.

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There is still much to be learned about the fungus and how it spreads. One concern is that doctors may be promoting its spread inadvertently when they prescribe antifungal medication as a preventive medication for patients who have received an organ transplant or who are undergoing chemotherapy.

"It's hard to eradicate from hospitals," Perlin said. Most fungal pathogens die when they leave the body, but this one persists for days.

"A bulk of the work has to happen at the facilities," said Tina Tan, the state epidemiologist for New Jersey. "They have to be aggressive in trying to implement good infection control to stem the spread."

Contributing: Ryan Miller, USA TODAY