The Last of Us: How Dangerous Are Fungi to Humans?

The series The Last of Us (“The Last of Us”, in free translation), from HBO Max, became a tremendous success. Based on the video game franchise of the same name, dystopia tells the story of Joel and Ellie, who fight for survival in the midst of an apocalyptic scenario caused by a pandemic of the fungus Cordyceps.

In fiction, the species infects humans and turns them into dangerous creatures with cannibalistic tendencies, like a species of zombies. Faced with the success of the game – and now the series – and after almost three years of a real-life pandemic caused by the coronavirus, the question remains: do these fungi exist and can they, in fact, cause any harm to humans? What are the real dangers? Understand next.

What is The Last of Us series fungus?

According to Flávio Cesar Viani, professor of the Biomedicine course at Cruzeiro do Sul University, Cordyceps is a genus that includes several species of fungi. They are distributed all over the world, mainly in tropical and subtropical regions with a hot and humid climate, including, therefore, Brazil.

But there’s no reason to worry. All species of the genus Cordyceps are entomopathogenic, that is, attack only insects. “Each species of Cordyceps attacks a single species of insect. In general, they attack several orders of insects, especially those in which butterflies and moths are found”, explains Flávio.

The professor of biomedicine, who is also a veterinarian and has a doctorate in Medical Mycology (the area that studies pathogenic fungi), explains that the fungi Cordyceps are unable to infect mammals such as humans. “The reasons are numerous, but we can summarize it in the inability of the fungus to break through our skin, in addition to the fact that our immune system is much more refined than that of insects”, he says.

Know more: Vaginal yeast infection: symptoms, treatments and causes

In insects, these fungi act as follows: they produce and disperse spores through the air which, when adhering to the exoskeleton (external skeleton) of the insects, germinate and start their growth process. “The fungus structures grow inside the insect, producing different enzymes that will digest it, as well as many toxins that will interfere with the animal’s physiology”, he explains.

But are these fungi able to control the functions of the hosts and turn them into true zombies, as happens in The Last of Us with humans? According to Flavio, no. “The aberrant behavior that insects show is the result of the destruction of their tissues and the large amount of toxins released”, he clarifies.

Which fungi are really dangerous for humans?

despite the Cordyceps not to attack humans and, much less, turn them into zombies, as happens in the series, you still need to be aware of some species. In the end, there are fungi that can cause dangerous diseases in people.

A good example are the yeasts of the genus Candida, responsible for banal superficial infections, such as ringworm, candidiasis and thrush, to serious infections that affect the nervous and urinary systems. Another example is the Cryptococcus neoformanswhich lives naturally in the soil and is spread by birds such as pigeons.

Read more: Ringworm: types and how to treat the infection

“In immunocompromised people, who acquire it through inhalation, it causes respiratory infections and infections in the central nervous system”, explains the professor of Biomedicine. “After inhaling this yeast, normally present in pigeon droppings, there can be both a severe pneumonia how much a encephalitis. The multiplication of this yeast in the brain will cause severe inflammation and, subsequently, the destruction of brain tissue. If not treated, it is fatal”, he warns.

There is also a kind of mold typical of Brazil, the Paracoccidioides brasiliensiswhich causes a disease called paracoccidioidomycosis. “Its spores enter the human body mainly through inhalation and the disease manifests itself in the respiratory and cutaneous form with ulcerations, and can even penetrate to the bones”, says Flávio. “This disease is more common in rural areas, where contact with the soil by workers favors its spread”, he adds.

Current threats: fungi that worry scientists

In addition to these species, there are some fungi that have recently attracted the attention of specialists and scientists. In the world, about 1.5 million people die each year from yeast infectionsaccording to the Society for Microbiology.

Last year, the World Health Organization (WHO) released a list of 19 fungal pathogens considered “a major threat”. One of them is yeast candida auriswhich caused worldwide impact for its resistance to antifungal drugs.

First identified a decade ago in South Korea, the candida auris it has already caused outbreaks in India, South Africa, Venezuela, Colombia, the United States, the United Kingdom, Spain and Japan. The transmission of this species takes place through the skin or mucosa and, when the fungus reaches the bloodstream, the chances of mortality are 59%. According to the National Health Surveillance Agency (Anvisa), the fungus has not yet been registered in Brazil.

Know more: How to treat skin fungus?

Another pathogen on the list is Aspergillus fumigatus, a fungus that causes lung disease in people with weakened immune systems. The list also includes the candida albicans, a yeast that lives in the mouth, intestines and skin and can cause vaginal infection, diaper rash or candidiasis in the event of an imbalance in the human body’s microbiome; and the Cryptococcus neoformanscited above.

In addition to these, a fungus present in Brazil has also raised the alarm. O Sporothrix brasiliensis was discovered in the 1990s, with the first cases of infection by this pathogen being registered in Rio de Janeiro. Gradually, the infections spread to other Brazilian states. Transmissions happen from cats to humans.

These micro-organisms penetrate the superficial layers of the skin, causing wounds and being able to invade the lymphatic system, affecting the eyes, nose and even the lungs. According to the Oswaldo Cruz Foundation (FioCruz), there were 178 cases of sporotrichosis – disease caused by fungus Sporothrix brasiliensis – between 1998 and 2001. According to doctor Flávio Telles, from the Brazilian Society of Infectology, in an interview with BBC News Brasil, there have been more than 12,000 cases in human beings since then.

How to prevent fungal contamination?

The prevention of fungal contamination is related traditional hygiene habits, as guided by professor of biomedicine Flávio. “Wash food well, do not put a dirty hand in your mouth, use properly sterilized nail instruments, perform medical examinations before entering public swimming pools and do not allow pigeons to multiply near human habitations, especially where there are vulnerable people, such as schools, hospitals and nursing homes”, he lists.