• The CDC says the fungus Candida auris has spread at an "alarming rate" in the U.S.
• Candida auris was limited to New York City and Chicago, but has since been detected in more than half of U.S. states and has become endemic in some areas.
• The fungus was first identified in Asia in 2009, and the initial U.S. case dates back to 2013.
• A growing number of samples are resistant to drugs used to treat fungal infections.

A fungus that is often resistant to drugs has spread at an "alarming rate" through health-care facilities in the U.S., according to the Centers for Disease Control and Prevention.

Candida auris is an emerging fungus that is serious and potentially fatal for hospitalized patients, particularly those with multiple medical problems.

The fungus was first identified in Asia in 2009, and the initial U.S. case dates back to 2013. Candida auris was limited to New York City and Chicago, but has since been detected in more than half of U.S. states and has become endemic in some areas, according to a CDC report published in the Annals of Internal Medicine on Monday.

From 2019 to 2021, 17 states detected their first-ever cases of the fungus. California, the mid-Atlantic region, the Midwest, Texas and Florida had growing transmission during that time, according to the CDC.

Infections have increased by about 200% from about 500 infections in 2019 to more than 1,400 in 2021. The fungus has spread most in long-term care hospitals for people who have serious medical conditions and need ongoing treatment, according to the CDC.

Symptoms can vary greatly depending on the type of infection, but fever and chills are the most common. People with weak immune systems, who have diabetes, who take a lot of antibiotics or who are are on breathing tubes, feeding tubes and catheters are more likely to be affected.

A 2021 CDC report found that mortality in two outbreaks of the fungus that was resistant to echinocandins was 30% over 30 days. The cases studied in the outbreaks were primarily severely ill patients at long-term care facilities, so the exact contribution of Candida auris to the deaths was unclear. The outbreaks took place in Washington, D.C., and Texas.

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Candida auris is often resistant to medication used to treat fungal infections. In 2020, 86% of samples were resistant to a class of antifungal drugs called azoles and 26% were resistant to amphotericin B, according to the CDC.

Just over 1% of samples tested in 2020 were strains resistant to the main drug class used to treat such infections, called echinocandins, up from 0.4% in 2018. The CDC said that although resistance to echinocandins is still uncommon, the number of such cases tripled in 2021 compared to the previous two years.

"Even this subtle increase is concerning because echinocandins are the first-line therapy for invasive Candida infections and most Cauris infections," the CDC said in its report.

The CDC attributed the rapid spread of the fungus to a decline in infection control during the pandemic due to strain on the health-care system, from staff and equipment shortages to a surge in patient burden and increased antimicrobial use.

"The rapid rise and geographic spread of cases is concerning and emphasizes the need for continued surveillance, expanded lab capacity, quicker diagnostic tests and adherence to proven infection prevention and control," said CDC epidemiologist Dr. Meghan Lyman, the lead author on the report.