Super fungi, a new and mysterious threat to global health

• Threat: More than 35,000 deaths annually in Spain because of the 'super bacteria'
• Spain: An outbreak of candidiasis with 40 affected at La Fe hospital

A threat against the health of humans, animals and crops has been growing silently over the past decades. Each of the large fungal families - Cryptococcus , Pneumocystis , Aspergillus and Candida - causes hundreds of thousands of deaths a year, to a total of 1.6 million worldwide , according to figures from the Global Action Fund for Fungal Infections (GAFFI). Almost as many as tuberculosis, the most lethal bacterial infection today. And the emergence of new strains, resistant to one or several antifungal drugs, further complicates the future of the fight against these diseases.

"The dimension of the problem has been poorly recognized and underestimated, but the risk it poses to human health and food security is serious and immediate," says Matthew Fisher, Professor of Public Health at Imperial College London and first author of a study on the growing presence of multidrug fungi in patients and cultures, appeared in a special issue of the journal Nature . "The threat posed by antimicrobial resistance is demonstrated in bacteria, but has been largely neglected in fungi."

This is the case of Candida auris, a superhongo discovered in 2009 and that has already caused victims on four continents. And Spain has been one of the most affected countries: more than half of the cases registered in Europe have occurred in our country. The largest outbreak in Spain occurred between 2016 and 2017 at the University and Politècnic La Fe Hospital in Valencia: more than 40 patients developed infections in a period of only 10 months. A year later, doctors from the Valencian center analyzed the episode in a scientific article published in the specialized journal Mycoses . In it they describe a fungus that attacks patients who already suffered from serious ailments and that presents an important resistance to antibiotics; two elements that explain its high mortality rate (41% in the first 30 days). It is estimated that there are about 1.5 million species of fungi, although most have not yet been cataloged by scientists. Only a few hundred have the ability to survive in the human body . By placing our body at 37 degrees, evolution has protected us from most of them. The rest, under normal conditions, are blocked by our immune system. “Many fungi, like some species of the genus Candida , are part of our natural microbiota, in the skin or in the mucous membranes of the intestinal tract,” explains Óscar Zaragoza, a researcher at the Carlos III Health Institute and author of the book Microscopic fungi: Friends or enemies ?, (Ed. The Falls).

Sickness of the sick

"But when our defenses go down they have the opportunity to replicate, spread through the body and invade our organs." Fungal infections are, in a way, diseases of the sick . That is why it is common for outbreaks to occur in medical centers. "The majority are opportunistic, they affect patients who already have some risk factor, mainly defects in the immune system," says the researcher.

In addition, mycoses and bacterial infections can manifest themselves with similar symptoms, which makes them difficult to diagnose, a circumstance that leads some authors to suspect that their incidence worldwide is even greater than is assumed.

In Valencia the outbreak could be controlled and no patient has developed infection over the last year, but in other regions of the world cases are increasing. In the United States C. Auris has caused almost 600 victims in the last five years. The New York Times published this spring a series of articles accusing hospitals in Europe and the United States of creating "a climate of denial and secrecy." The American newspaper maintained that these centers - including La Fe - had done their best to keep the problem hidden from the public, since "they were concerned about the image of the hospital."

From the Levantine center they deny that there was any will to keep the outbreak hidden and ensure that «the usual protocol was applied in these cases and was communicated to the General Directorate of Public Health of the Department of Universal Health and Public Health of the Generalitat Valenciana. They also point out that "all media outlets who were interested in the subject were informed, including The New York Times" and that if a similar case occurred in the future it would apply exactly the same procedure.

Fungicide Abuse

Perhaps the mystery surrounding C. auris is related to the little that is known about its origin and spread, two elements that are currently under intense investigation. Catheters, thermometers and other elements of the sanitary material have been indicated in different scientific articles as possible vectors of infection , once the outbreaks burst. Nor is its origin clear, although scientists agree that the excessive use of drugs and fungicides in the health and agri-food sector has favored its development and that global trade has favored its territorial expansion.

"The molecules of some of the fungicides are very similar to those used to treat patients, therefore to maintain their effectiveness it is important to avoid their dispersion throughout the environment," explains Stephan Bretagne, professor of molecular mycology at the Institute Pasteur of Paris. "The authorities are already aware of the intensive use of antifungals in agriculture and are being phased out."

But fungal infections not only affect human health, they also ballast world crops and are decimating amphibian populations across the globe. The two main diseases of wheat, septoriosis and black rust, both of fungal origin, would be reducing world production by 20%. That means that with the losses they cause, 60 million people could be fed. The same goes for rice, soy, corn and potatoes. "If these five grains suffered a simultaneous epidemic, 39% of the world's population would be threatened with food security," warns Sarah Gurr of the Department of Plant Science at the University of Oxford, co-author of the article published in Nature.

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