EXCL: CDC's Fungi fighter reveals why the next pandemic could be a mutant fungus that causes skin boils and brain swelling

It was the gruesome fantasy show that put fungus on the map.

The Last of Us, based on the popular video game of the same name, saw a group of intrepid explorers trudge their way across a dystopian American landscape in search of a way to beat the uncontrollable fungus that co-opted billions of people's brains and turned them into mindless, flesh-eating zombies. 

While the real-life impact of fungal outbreaks is not as fantastical - there is more than a grain of truth to such a scenario, a top expert in the field has told DailyMail.com.

In fact, according to CDC fungal expert Dr Ian Hennessee, the US could soon be grappling with a rise in new fungal infections that can block breathing, cause unsightly, agonizing boils to appear on the skin, or cause deadly brain swelling that ultimately results in death.

The Blastomyces species is among the most pressing threats, in addition to Candida auris and valley fever-causing coccidioides, according to Dr Hennesse - which is why he has dedicated most of his career to researching fungi. 

Dr Hennessee said: ‘The Last of Us brought the fungal diseases [to the fore]. They're often not the first ones that the clinician will even think of.

‘We are encouraging people to think fungus because these fungi are out there. They often are rare, but when people get them, they're oftentimes misdiagnosed and underreported. And that can cause really severe disease.’

Dr Ian Hennessee [pictured] is a disease investigator for the CDC with a specialty in fungal diseases. He helped lead a thorough surveillance project into a devastating blastomycosis outbreak at a Michigan factory last year

Blastomycosis typically arises from exposure in wet environments, primarily in the upper Midwest. But epidemiological studies are increasingly finding the fungus on the East Coast

Climate change is making the threat of widespread fungal diseases all the more realistic, as warmer temperatures and humid conditions allow species longer time every season to thrive and spread their spores. 

The fungus that causes valley fever, coccidioides, thrives in hot desert environments that are now continuously getting hotter and drier. And another, Histoplasma, which causes histoplasmosis, thrives in wet soil on the East Coast, which is getting more and more rain each year.

In the west, Valley fever is sickening more people than ever, with cases in California tripling from 2014 to 2018 and from 2018 to 2022.

Meanwhile Candida auris, a species of particular concern to disease investigators like Dr Hennessee, infected approximately 2,400 Americans in 2022, up from 480 in 2019. Between 2013 and 2016, there were only 63 cases.

Blastomycosis, which arises from breathing in the spores of the blastomyces fungus, is also becoming more and more common. Last year, Dr Hennessee helped investigate a massive outbreak at a Michigan paper mill that sickened more than 100 people and killed one. 

And earlier this year, researchers found evidence of more than 100 cases of blastomycosis in Vermont, where the blastomyces fungus is not typically found. 

Dr Hennessee told DailyMail.com climate change has helped the fungus widen its reach, hitting new areas where it was not previously endemic, including Vermont. Developing drugs that can outlast the fungi's ability to sidestep them is crucial to beating back the public health threat. 

He said: ‘As we see changing environmental conditions, we are concerned about changing distribution, or even the impact of some of these fungal diseases, not just blastomycosis, some of the other ones, histoplasmosis, valley fever and things like that.’

In Michigan, 29-year-old Ian Pritchard became one of the first Americans of 2024 to have succumbed to blastomycosis, the second member of his family to die of it. 

And in 2020, Ira Walker became infected. Ira languished in the hospital for a month after doctors surgically engineered an opening through his neck to his trachea, before being moved to a specialist facility for a higher level of care. 

Ian Pritchard was in a medically-induced coma in a Detroit hospital before passing away from a fungal infection

Ira Walker, pictured left, succumbed to blastomycosis in 2020. His wife Lorelei, shown right, told DailyMail.com that she still does not know how he got sick

While the hope was for him to regain lost strength and muscle mass, his situation only got worse.

His wife Lorelei told DailyMail.com: ‘Instead of regaining his strength, he became weaker. Every time the hospital would call, there would be news of yet another setback.’

Blastomycosis is not reportable in any but six states, meaning the federal government lacks a solid grasp on its exact prevalence.

When spores are breathed in, the blastomyces fungus undergoes a transformation into a type of yeast that becomes embedded in lung tissue, appearing as opaque masses on X-rays. Because of this, it is often mistaken for pneumonia. 

People with the infection may suffer from flu symptoms. In serious cases, they can progress within days to weeks to suffering from pneumonia, lesions on the skin — which appear as raised bumps, blisters, or ulcers — and neurological problems such as encephalitis or brain swelling.

The infection is not spread person-to-person. Instead, the fungus infects people when they breathe in its spores. It often hides in rotten wood and leaves.

The fungus that causes Valley fever thrives in hot, dry environments

Though it can be found in wood pulp that people handle in the early stages of paper production, the cases of blastomycosis at the Michigan paper mill were not limited to that part of the factory.

Dr Hennessee said, ‘there wasn't a smoking gun or a single place that we could point to and say, Everybody got it here, and nobody got it there.

‘Instead, it kind of pointed us towards, Okay, well, could there have been sort of broad environmental exposure? Maybe people are being exposed as they're, you know, parking and walking towards the mill,’ which is next to a river.

He added that the spores could have blown indoors, possibly being the cause of sickness across stages of production.

The surveillance and warning efforts were extensive. Investigators like Dr Hennessee raced across Escanaba, Michigan to knock on doors asking people whether they worked at the plant, if they hiked often, or if they rode ATVs through the woods.

He and fellow National Institute for Occupational Safety & Health investigators held town hall meetings with employees. 

They eventually told workers to wear N95 respirators.

Deadly fungal diseases have become more common recently, from 4,746 cases in 2018 to 7,199 in 2021. And climate change appears to be driving it. 

Mother-of-one in Wisconsin, 31, dies from fungus growing rapidly in US 

Sonya Cruz, 31, from Kenosha, Wisconsin, died on July 5 from blastomycosis - an illness caused by the fungus blastomyces, which is mainly found in soil in wooded areas. 

Dr Hennessee said: 'We might see it in areas outside of what we considered it's historically endemic range. We've never really seen it in a big industrial setting before [the Michigan outbreak] so it's possible sometimes we'll see it in other in other areas where we just didn't.' 

He added: 'But testing for it is limited testing for it is limited. We don't have great environmental sampling. And it's not always easy to say, Hey, is it in a new place? Or is it just that we're looking for it in this new place?' 

One report in 2022 found that around 10 percent of blastomycosis cases are diagnosed in areas separate from where the fungus is known to thrive as warming temperatures expand their endemic range.

A deadly combination of international travel and climate change makes infections more prevalent. 

In Vermont, where winters are very cold and spring and summer are mild, has gotten balmier and balmier in the past decade, allowing non-native fungi to thrive.

Dr Hennessee said: ‘We definitely are concerned as temperatures change, environmental conditions are changing. And so many of the fungi that we work on, Blastomyces included, definitely are very climate sensitive or sensitive to changes in temperature, rainfall, things like that.

‘The work from Vermont is a good example, where we do see it being detected in areas outside of what we thought was the historic range.’

Blastomycosis is far less common and not transmissible like another troublesome disease-causing fungus, candida auris.

C. auris kills around one in three people that become infected. It is resistant to most antifungal infections, making it a pronounced concern for disease investigators.

The yeast is highly transmissible and easily spreads by touching contaminated surfaces among patients with weakened immune systems. 

Infections can potentially trigger deadly sepsis. It’s primarily a problem in healthcare settings and is rarely a problem for the general population.

Dr Hennessee said: ‘It can cause more kinds of healthcare-associated outbreaks and it can spread pretty pretty quickly. And it is also frequently very drug-resistant.

‘We worry about that one, and it is spreading quite quite rapidly globally in healthcare settings, specifically.’