Spread and surveillance

A drug-resistant fungus is spreading across the United States, with 3,437 clinical cases documented nationwide this year in 27 states, according to data from the Centers for Disease Control and Prevention. Candida auris, called a “superbug” due to its resistance to treatment, was first discovered in 2009, and the first clinical cases began appearing in 2016, the CDC said.

In 2024, there were 6,304 new clinical cases of Candida auris in the United States, according to the CDC. The total number of U.S. clinical cases has increased each year since the first U.S. case was reported in 2016, but in recent years, the rate of increase has been slowing down, according to the federal agency.

Dr. Ulysses Wu, an infectious disease specialist with Hartford HealthCare, attributes part of the rise to better detection. “Candida auris is becoming more common because we are now looking for it,” Wu said, adding that he has no doubt it’s in every single state and a lot of facilities probably have it.

Who is at risk

The fungus mostly affects patients with severe underlying medical conditions who require complex medical care, Wu said. Patients with invasive medical devices like breathing tubes, feeding tubes, and catheters are at increased risk for infection. Residents in long-term care facilities like nursing homes are also at risk.

“Anyone who resides in long-term care facilities is vulnerable,” Wu said.

Candida, a genus of yeasts, is the most common cause of fungal infections worldwide. The genus encompasses about 200 different species, most of which are reactive to treatment. Candida auris is one of the few yeast species that has become resistant to several drugs.

Colonization versus infection

An important distinction is between clinical infection and colonization. People without risk factors generally do not get sick or display symptoms from Candida auris. Those with healthy immune systems may test positive for colonization of the fungus but have no outward symptoms. Good immune systems typically fight off the fungus easily, according to the CDC. Most healthy people do not have the fungus on their bodies.

Hartford HealthCare has an active screening protocol to look for Candida auris in people who may be at high risk, Wu said. The health system has found the fungus a few times over the years, mostly colonizations rather than infections.

How it spreads and prevention

Daily life and casual contact do not spread Candida auris to healthy people, and it cannot be transmitted like a virus. The fungus is spread more from direct contact through either the body or the secretions of a person who is infected, or indirect contact with contaminated medical equipment or surfaces, according to Dr. David Calfee, an infectious disease specialist.

Hospitals and long-term care facilities can use cleaning protocols to minimize potential spread of the fungus, Calfee said.

Regional data and outlook

Connecticut reported 12 clinical cases of Candida auris infection in 2024, according to CDC data. Before 2024, Connecticut had between one and 10 reported cases per year. From 2016 through 2024, Connecticut reported a total of 20 clinical cases. Neighboring New York reported the most cases with 460 in 2024.

Calfee said that total eradication of Candida auris is unlikely. Initially it was difficult to detect and was misidentified in the past, but more laboratories are able to detect it now, allowing for better monitoring. The fungus most likely will continue to be reported, as it has become easier to detect and healthcare providers have become more familiar with it, he said.