Fungal infections “increased significantly” among hospital patients during the COVID pandemic, says the World Health Organisation as it released its first-ever list of fungi posing the greatest threat to human health.

The WHO’s report, outlining fungal “priority pathogens”, warned some strains are increasingly drug-resistant and becoming more widespread.

Only four types of treatments exist, with very few new options in the development pipeline, it said.

Climate change means the incidence and geographic range of the pathogens is expanding, while resistance is partly driven by the over-use of antifungals in agriculture, according to the WHO.

People at the most risk of invasive fungal infections include those with cancer, HIV/AIDS, organ transplants, chronic respiratory disease, and post-primary tuberculosis infection, it warned.

The WHO’s fungal priority pathogens list features 19 fungi that represent the biggest public health threat.

The list separates the pathogens into three categories – critical, high and medium priority – based on their potential impact and data on their resistance risk.

Candida auris, Cryptococcus neoformans, Aspergillus fumigatus and Candida albicans are classified in the highest ranked “critical” group.

Candida auris is highly drug resistant and has caused a number of outbreaks in hospitals worldwide. It is an emerging fungal infection that also causes infections primarily in people with weakened immunity.

It is a globally distributed pathogenic yeast that can cause invasive candidiasis of the blood (candidaemia), heart, central nervous system, eyes, bones and internal organs.

The overall mortality risk of invasive candidiasis with Candida auris ranged from 29% to 53%.

Cryptococcus neoformans is an infection that tends to affect people with immune deficiency such as HIV, or cancer, and can cause meningitis.

Cryptococcosis, caused by Cryptococcus neoformans, can be life-threating, with a mortality risk of 41% to 61%, and cause complications such as blindness and kidney impairment.

Aspergillus fumigatus is a common mould that is widespread in the environment in people’s homes and outdoors. It tends to cause lung problems often in people with some existing lung problem and can cause an asthma like illness, pulmonary fibrosis or a non-cancerous tumour.

Candida albicans is the principal cause of thrush which is a common and unpleasant illness. However, in people with weakened immune systems it can cause a range of severe diseases including meningitis and septicaemia.

Worldwide public health concern

Clinical trials aimed at reducing morbidity and mortality are needed, the report outlined.

The number of fungal infections and how far they spread worldwide could be expanding due to climate change and the rise of international travel and trade, said the WHO.

However, due to the scarcity of quality data on fungal infections, and the lack of attention they receive, the extensiveness of the threat fungal diseases and their resistance to treatment can pose is unknown.

The WHO has called for governments and researchers to step up their response to the 19 fungi on the list.

“Emerging from the shadows of the bacterial antimicrobial resistance pandemic, fungal infections are growing, and are ever more resistant to treatments, becoming a public health concern worldwide,” said the organisation’s Dr Hanan Balkhy.

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