A mysterious and dangerous fungal infection called Candida auris has emerged around the world. It is resistant to many antifungal medications, placing it among a growing number of germs that have evolved defenses against common medicines. Here are some basic facts about it.

What is Candida auris?

Candida auris is a fungus that, when it gets into the bloodstream, can cause dangerous infections that can be life-threatening. Scientists first identified it in 2009 in a patient in Japan. In recent years, it has emerged around the world, largely in hospitals and nursing homes. There have been 587 C. auris cases reported in the United States, according to the Centers for Disease Control and Prevention, most of them in New York, New Jersey and Illinois.

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Why is it so dangerous?

C. auris is often resistant to major antifungal drugs that are typically used to treat such infections. The C.D.C. says that more than 90 percent of C. auris infections are resistant to at least one such drug, while 30 percent are resistant to two or more major drugs. Once the germ is present, it is hard to eradicate from a facility. Some hospitals have had to bring in special cleaning equipment and even rip out floor and ceiling tiles to get rid of it.