An infectious, drug-resistant fungus that kills about half of the people it infects is spreading around the globe, including the United States.

The Centers for Disease Control and Prevention (CDC) reports that there are 685 cases confirmed in the U.S. of the serious and sometimes deadly fungal infection Candida auris. The infection is often spread in health care settings.

The CDC has called it "a serious global health threat" and has added it to a list of now three urgent antibiotic-resistant threats.

Most C. auris cases in the U.S. have been detected in the New York City area, New Jersey and the Chicago area, but cases have been confirmed in 12 states.

Understanding this new threat

A strain of Candida auris cultured in a petri dish at the CDC. A strain of Candida auris cultured in a petri dish at the CDC. (Photo: CDC)

The CDC is concerned about C. auris because it's often resistant to the antifungal drugs commonly used to treat other Candida infections. It's also difficult to identify and diagnose with standard testing methods, leading to inappropriate, ineffective treatment.

The fungus can also spread rapidly in health care settings. Most Candida do not spread from person to person, but C. auris does. The CDC says what is "different and particularly scary" about C. auris is that it can last on skin and surfaces like chairs and bedrails for a long time, which allows it to spread from person to person in health care settings.

Although anyone can be susceptible to an infection, risk factors include patients with diabetes or who've had recent surgery or central venous catheter placement or those using broad-spectrum antibiotics and antifungals. It targets people with weakened immune systems such as the elderly and infants.

Nearly half of the patients who contract C. auris die within 90 days, according to the CDC.

The CDC is recommending that doctors use special cleaning and disinfecting protocols to protect against C. auris. The agency is also working with labs to make sure they're using the correct tests to diagnose the fungus.

Understanding the origins

C. auris was first identified in Japan in 2009, where it was found in the ear canal of a patient who complained of an ear infection. Although "auris" is the Latin word for ear, the fungus can affect many other regions of the body, according to the CDC.

The fungus then started showing up in patients in hospitals in Asia, Africa and South America and no one could figure out any clear link between them.

"What is unusual about Candida auris is that it appeared in three different continents at the same time, and the isolates from India, South Africa, and South America are not related. Something happened to allow this organism to bubble up and cause disease. We began to look into the possibility that it could be climate change," said Dr. Arturo Casadevall, chair of the molecular microbiology and immunology department at the Johns Hopkins Bloomberg School of Public Health and lead author of a new study published in the journal mBio.

Fungal infections are rare in humans because most fungi can't grow in temperatures as warm as the human body. In researching relatives of C. auris, Casadevall’s team were led to believe that this fungus may have adapted to higher temperatures.

"What this study suggests is this is the beginning of fungi adapting to higher temperatures, and we are going to have more and more problems as the century goes on," said Casadevall in a statement. "Global warming will lead to selection of fungal lineages that are more thermally tolerant, such that they can breach the mammalian thermal restriction zone."

The fungus has now been reported in more than 30 countries including Canada, Colombia, India, Israel, Kenya, Kuwait, Pakistan, South Africa, South Korea, Venezuela and the United Kingdom.

Editor's note: This story has been updated since it was originally published in November 2016.

Mary Jo DiLonardo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.

What is Candida auris?
Drug-resistant and sometimes fatal fungus Candida auris has been found in the U.S., and it's hard to detect.