A recent report from the Centers for Disease Control and Prevention revealed the fungus Candida auris is spreading rapidly through U.S. health care facilities.
Also known as C. auris, reports of cases linked to the drug-resistant fungus have doubled in 2021.
In addition, the fungus is behind an outbreak in Mississippi that began in November, infecting at least 12 people and potentially responsible for about four deaths, according to figures provided by the state Department of Health to ABC News.
Although C. auris does not present a threat to most healthy people, and infections are rare, it can affect vulnerable groups of people and can be resistant to several classes of drugs.
Here's what to know about the fungus, why these rare cases occur and how Americans can help prevent the spread.
What is Candida auris?
"C. auris is a species of Candida and Candida is the most common yeast that causes human infections," Dr. Shira Doron, chief infection control officer for Tuft Medicine, told ABC News. "People are quite familiar with the term 'yeast infections' or 'thrush'; those are caused by other species of Candida."
According to the CDC, it's a relatively new type of fungus, being first identified in Japan in 2009.
However, studies conducted since then have found samples of C. auris can be dated back to South Korea in 1996.
Public health experts refer to C. auris as an emerging pathogen, which means an organism that has newly appeared or been discovered but has since rapidly spread -- either in terms of cases or countries where it is now reported.
Why is C. auris potentially dangerous?
Dr. Scott Roberts, associate medical director of infection prevention at Yale School of Medicine, told ABC News that C. auris can spread either from person-to-person transmission or by people coming into contact with contaminated surfaces.
"This spreads person to person and we do not think of really any other fungus as spreading person to person in a meaningful way," he said. "And it's really hard to kill. Standard Lysol wipes, disinfectant wipes don't kill it. We need dedicated bleach wipes or additional products geared for Candida auris."
The other issue is there are strains of C. auris that are drug-resistant, meaning infections caused by the yeast will not respond to multiple antifungal drugs commonly used to treat Candida infections.
How is it diagnosed?
Patients with C. auris infections are typically diagnosed after cultures of blood or other bodily fluids are analyzed.
However, experts said this can be difficult because analyzing these cultures requires updated machines or updated libraries, not all labs of which have the capability.
Additionally, it can be hard to identify C. auris on the culture results and it can be confused with other species of Candida.
"The way cultural results come back, first it's like, 'Okay, it looks like yeast,'" said Doron. "Then it's like, 'Okay, it looks like Candida' only it could take days before it's Candida auris and you may be using the wrong drugs."
Who is at risk?
Most healthy people do not need to worry about C. auris infections, experts said.
However, those with weakened immune systems or who are immunocompromised are at risk of hard-to-treat infections.
Additionally, nursing home patients or hospital patients who have or have had lines and tubes in their body -- such as a catheter or a breathing tube -- are also at high risk.
How are C. auris infections treated?
Despite several strains C. auris infections being multi-drug resistant, there is a class of antifungal drugs called echinocandins that can be used and are given intravenously.
According to the National Institutes of Health, echinocandins prevent a key enzyme needed to maintain the cell wall of the fungus.
In some cases, when the infection is resistant to all three main classes of drugs, multiple high doses may be required, the CDC said.
Are C. auris infections fatal?
According to the CDC, studies are limited but anywhere between 30% and 60% of people with C. auris infections have died.
However, many of these patients also had other serious illnesses that also increased their risk of death.
"Unless there's a break in the skin or some sort of deeper systemic infection, the risk of mortality, or some deeper complication, is relatively low unless that fungus gets in a place that it should not be," Robert said. "For example, there's a break in the skin, it gets in the bloodstream and there's a Candida auris blood stream infection, and that can be quite fatal."
He continued. "Candida auris, it sticks to everything. It can stick to heart valves and stick to catheters. I do want to emphasize that's a rare occurrence, though."
What can we do to prevent the spread?
There's not much that can be done on an individual level to prevent the spread of the fungus, but the experts recommend avoiding patients with C. auris infections and that people practice proper hand hygiene when visiting at-risk populations such as hospital patients or nursing home residents.
Doron said people also need to be careful about the overuse of antibiotics. While they can be helpful in treating some infections, these medications can kill off bacteria in the gut and give more room for yeasts like C. auris to grow.
Roberts said there needs to be continued focus on equipping more labs to easily identify C. auris and focus on public health infrastructure that can identify, isolate and group patients who are infected.
"There's many examples of this but, you know, a nursing home, a patient has Candida auris," he said. "They spread it to their roommate, for instance. It's really critical in that standpoint to have a mechanism to test everyone else in the nursing home to see who's infected, put them in an isolated area, like one hallway, and put those who aren't colonized in the other hallway."
Roberts continued, "And if that patient needs to get admitted to the hospital, we let the hospital know this patient should be in Candida auris isolation. Don't reuse blood pressure cuffs on that patient and go to the next patient, for instance."
ABC News' Aerial Petty contributed to this report.