The potentially deadly fungus Candida auris is spreading rapidly in the US.

The fungus Candida auris has become a growing public health threat as the number of drug-resistant cases tripled in 2021, the Centers for Disease Control and Prevention said Monday.

The fungus is resistant to several antifungal drugs, but the CDC said it is not seen as a threat to healthy people. However, the National Public Health Agency lists C. auris as a major threat due to its drug resistance. It can cause serious illness and death in people who are already ill, use invasive medical devices, or stay in health care facilities for long or frequent periods.

Between 30% and 60% of infected people died from the yeast, according to the CDC, although this is “based on information from a limited number of patients.”

“The rapid growth and geographic spread of cases is worrying and highlights the need for continued surveillance, increased laboratory capacity, faster diagnostic tests, and adherence to proven infection prevention and control practices,” said CDC epidemiologist Dr. Megan Lyman.

Candida auris has been reported in over 30 countries and was first detected in the US in 2016. Since then and through December 2021, there have been 3270 clinical cases in the US in which patients were infected and 7413 CDC screenings reported that the fungus was present in patients but did not cause infection.

It can be spread from person to person or through contact with contaminated surfaces.

The number of cases may have increased so rapidly due to a lack of prevention, poor monitoring practices in healthcare facilities, and better case-finding efforts, according to the CDC.

Yeast is identified by testing body fluids, but has alarmed the CDC because it is harder to distinguish from other yeasts and can be misdiagnosed, making it difficult to contain.