Every day we inhale thousands of germs fungi They are potentially pathogenic, but our immune system simply eliminates them. In immunocompromised people – such as transplant recipients, patients undergoing cancer treatment or hospitalized in intensive care units (ICUs) – however, this interaction between pathogen and host can be very different.

An example is the fungal infections that emerged during the pandemic and reinforced the impact of the SARS-CoV-2 virus on the planet. Among patients with a severe form of COVID-19 And infected with fungus at the same time Aspergillus smokeThe mortality rate was 80%.

An international group of researchers has conducted an overview of the burden of this common infection (coronavirus and fungi) in the world during the health crisis. work was published in Nature Microbiology It brings alerts for this and future epidemics.

“Fungus is a highly neglected public health problem with few treatment options. Currently, there are more deaths from fungal diseases than from malaria and tuberculosis combined, for example. Therefore, it is not surprising that fungal diseases benefit from the introduction of many people hospitalized with Covid-19,” says Gustavo Henrique Goldmann, professor at the Ribeirão Preto School of Pharmaceutical Sciences, University of São Paulo (FCFRP-USP) and one of the study coordinators, supported by FAPESP.

In addition to aspergillosis, a disease caused by fungi of the genus Aspergillus fungusThere are two other groups that cause co-infection with Covid-19. You are Mucosa It is responsible for mucositis, which occurs mainly in India and Pakistan. yeasts of the sex candidain turn, the reason Candidiasis They are present practically on the entire planet.

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Aspergillosis associated with Covid-19 [condição denominada CAPA, na sigla em inglês] It affects an average of 10% of patients with acute respiratory failure admitted to the intensive care unit. Carriers of this co-infection are twice as likely to be fatal compared to individuals infected with SARS-CoV-2 alone,” a professor at the University of California San Diego, in La Jolla, in the United States, tells Agência FAPESP Martin Hönigl. States, University of Graz , Austria, first author of the study.

Losses and gains

According to the article, aspergillosis can be confined to the upper airways for several days and can be contained with antifungals. Once it invades the vasculature of the lung, the mortality rate is over 80%, even if systemic antifungal therapy is given.

Candidiasis occurs almost exclusively in intensive care unit patients, and is no longer more common in Covid-19 patients than in patients hospitalized for other reasons. However, fungi are a new emerging species Candida auris-Worry about the ability to colonize the skin.

They also seem to be the only ones that pass from person to person. This type is resistant to all known antifungals, and because it is present in different environments, it can easily reach patients through tubes, ventilators and other invasive life support equipment found in hospitals.

Mucositis associated with Covid-19 is a particularly serious problem in India, where the number of cases has doubled compared to the period before the epidemic. Reports of this mycosis gained international attention in 2021, when more than 47,500 cases were reported in that country between May and August alone.

Considered, at the time, an epidemic by the Indian government, the mucous membrane fungus was mistakenly called “black fungus”, due to the appearance of dead human tissue resulting from the disease. In fact, the black fungus belongs to another group that is relatively distant from Mucosa , It does not cause disease to humans.

In patients with COVID-19, mucositis most often occurs in the eye and nose area, and can reach the brain. In these cases, the association between the two diseases has a mortality rate of up to 14%. Because it causes necrosis, the injury in many cases requires surgical operations that disfigure the patient.

When they survive, they can lose parts of their face, and face various problems for the rest of their lives. When a fungal infection infects the lung or spreads through the body, the mortality rate is up to 80%.

“The prevalence of this mycosis in India was 0.27% in hospitalized patients with Covid-19, although it can often occur in out-of-hospital patients, such as those treated at home with very high doses of systemic corticosteroids readily available to the general population. .from that country,” says Hönigl.

The use of this drug and other classes of drugs that reduce immune activity is one of the reasons for the increase in fungal infections worldwide. However, the strategy has proven successful during the pandemic, where the benefits outweigh the risks. However, researchers cautioned about the importance of avoiding abusive use of immunosuppressive drugs.

Alternatively, some high-risk centers for aspergillosis have successfully implemented prophylactic antifungal therapy, with drugs administered even before infection with these agents. But because fungi are often resistant to most available drugs and there are not enough clinical studies to evaluate this strategy, it is not currently recommended.

new drugs

Global warming It also paves the way for many fungi to adapt to higher temperatures, making humans more vulnerable. Therefore, experts agree that the development of new antifungal drugs is urgent. There are currently only four classes of these drugs, compared to dozens of different classes of only antibacterials, for example.

Another problem is the difficulty of diagnosis, which can be costly by the standards of low- and middle-income countries or cannot be done with the speed necessary to determine the ideal treatment.

For 100% confirmation of the presence of aspergillosis, for example, a bronchoscopy examination is necessary – something considered risky during the Covid-19 pandemic. That’s because the amount of human fluid expelled during the procedure is more than enough to transmit the SARS-CoV-2 virus to medical staff.

“Fortunately, there is good news for drug development in this area, with several new classes of antifungals in phase II and III clinical trials,” says Hönigl.

However, researchers fear that these new drugs will not reach everyone who needs them and that cutting-edge treatments will remain limited to rich countries.

In this scenario of global warming, few drugs and diseases are available that weaken and cause epidemics and epidemics, and new outbreaks of fungal infections will occur again. We need more tools to control it and more researchers to study different fungi and their mechanisms of action,” concludes Goldman.

*This content is from Agência Fapesp.