The deadly, drug-resistant fungus Candida auris has spread faster and has become even more resistant to drugs amid the COVID-19 pandemic, according to researchers from the US Centers for Disease Control and Prevention (CDC), wrote ArsTechnica.

The parasitic yeast Candida auris has been considered an “urgent threat” — the CDC’s highest level of concern — since it was first reported in the United States in 2016. Candida auris is one of the causative agents of human candidiasis. The species was first described in 2009, when it was discovered in the ear sample of a 70-year-old Japanese woman in a Tokyo metropolitan hospital suffering from otomycosis (an ear fungal infection). Subsequently, Candida auris spread in many countries of the world.

The fungus affects the circulatory system, central nervous system, kidneys, liver, bones, muscles, joints, spleen and eyes. The disease occurs in patients with weakened immunity, with concomitant diseases, such as diabetes, some lung and kidney diseases. Therefore, Candida auris is often found in medical facilities, where vulnerable patients are more likely to become infected. The fungus is quite resistant to antifungal drugs and can live on walls and furniture for several months. Due to the invasive infections caused by it, the mortality rate reaches from 30 to 60%.

In 2019, before the pandemic began, 17 states and Washington, DC reported 476 clinical cases of Candida auris. But in 2020, eight more states reported cases for the first time, and the total number of clinical cases increased by 59% to 756. In 2021, 28 states were affected and the number of clinical cases almost doubled to 1,471. The number of asymptomatic cases detected during patient screening, has also increased dramatically amid the pandemic, tripling from 1,310 cases in 2020 to 4,041 cases in 2021. These data were published on Monday in the Annals of Internal Medicine journal.

“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,” Meghan Lyman, a CDC epidemiologist and lead author of the study, said in a statement.

But the spread of Candida auris was not the only worrying aspect of the fungal pandemic activity. It also became more resistant to medication. Before the pandemic, only six patients developed infections resistant to first-line antifungal drugs, echinocandins. But in 2021, there were already 19 such cases. Also, before the pandemic, there were four reports of pan-resistant infections, that is, the fungus was resistant to all available drugs. However, in 2021, seven patients with pan-resistant infections were already recorded.

Before the pandemic, cases of resistance to echinocandins and panresistance developed in patients independently of each other against the background of continuous treatment – that is, they were isolated cases that were not transmitted from person to person. But the 2021 cases identified two outbreaks of echinocandin-resistant and pan-resistant strains with human-to-human transmission.

“The timing of this increased C. auris spread and findings from public health investigations suggest it may have been exacerbated by pandemic-related strain on the health care and public health systems,” Lyman and colleagues concluded in the study.

CDC researchers suspect that a shortage of staff and personal protective equipment may have contributed to the spread of the fungus, as could changes in patient movement and increased use of antimicrobials.

They also suggest that while special infection control measures were stepped up during the pandemic, others took a back seat, such as environmental disinfection, which may have led to increased spread of Candida auris. The researchers called for renewed efforts to contain the transmission of the infection.