Lindsey Hall’s boyfriend was asleep on her shoulder when she accidentally discovered what he’d been telling ChatGPT about her.

Her phone had died, so she picked up his to look up something for work. Then she noticed a chat titled “Relationship Issues and Uncertainty.” Inside, she says, were complaints about her appearance, doubts about his attraction to her, and a sentence she still remembers verbatim: “I’m just not proud of her.”

While he peacefully snoozed beside her, she learned that ChatGPT had issued a verdict on the state of their relationship: Her boyfriend needed to end it.

When she first saw the chat title, Hall figured it was about a familiar disagreement: She loved her three cats; he wasn’t an animal person. “This is probably about the cats,” she remembers thinking. She hadn’t expected a list of complaints about her. “Nothing was positive,” she says. “Not one thing.”

Hall got up, collected her toothbrush and charger, and slipped out the front door. “I just had nothing to say,” she says. “I had nothing but rage at that point.”

Couples have long had ways to discover things they weren’t supposed to know about each other: rifling through a journal, stealing a glance at incoming texts, poking around in Instagram or Snapchat DMs. Now, there’s another place to look—and plenty to wish you hadn’t seen. Therapists say they’re working with couples who have discovered their partners asking AI whether they should break up, sharing sexual fantasies, or contemplating how to bring up something they were too nervous to say out loud.

Why a partner’s AI chats can feel like a betrayal

Reading the chats doesn’t necessarily tell you what the other person meant. Was your partner venting after a fight or seriously considering leaving you? Were they asking for help talking to you—or finding a way to avoid it? And who owes whom an apology: the person who read the chats, or the one who shared intimate details about their partner with a chatbot?

When Ilana Grines, a licensed marriage and family therapist in Los Angeles, works with couples, her first question is now: “What have you told AI?” She wants to know if and how both people are using it, what they’re sharing, and whether they’ve discussed any of that with each other. Most haven’t, she says.

“We don’t have a language around our conversations with AI,” Grines says. Couples may understand that a journal is private without having discussed whether the same goes for a chatbot conversation. When someone discovers their partner’s chats, “it creates this huge rupture where one person accessed the other person’s history,” Grines says. “And then it’s nuclear.”

One couple Grines worked with paid for a single AI subscription. The wife, a teacher, used it to grade papers. Her husband used it to explore sexual fantasies, apparently without realizing that conversations from his computer would be visible through their shared account, Grines says. His wife discovered the topic in the platform’s sidebar.

“We know about a third person entering our relationship,” Grines says. “But we don’t know about this third space that we’re creating.”

Sometimes, one partner doesn’t even know that space exists. They might be aware their partner asks AI for help with work or vacation planning—not that they’re also discussing their sex life or wondering whether to stay together. Hall used chatbots herself, but discussing her relationship with one hadn’t occurred to her. “I just didn’t think of it as a tool for that,” she says.

Part of what stings is realizing your partner talked to a chatbot about something they felt like they couldn’t bring up with you, says Shemiah Derrick, a relationship therapist in Chicago. You might also wonder how long they’ve been feeling this way—and whether you would have known if you hadn’t read the chats.

Derrick has seen couples finally talk through a problem—only to start fighting when one person admits they used AI to figure out what to say. The other person’s reaction, as she describes it: “You had to go to chat for us to do that?”

In those cases, Derrick points out that the person turned to AI because their usual way of bringing up problems wasn’t working. They wanted to get through a tough conversation without having the same old fight. “They were trying to do something different,” she says.

What AI chats can reveal about relationships 

Giulia P. Davis, a licensed marriage and family therapist in San Francisco, recalls working with a couple after one partner read the other’s AI chats without permission and found complaints and doubts about their relationship. The person who wrote them was still sorting out how they felt. Their partner assumed they’d already made up their mind.

“The partner didn’t find a straightforward confession or plan to leave the relationship,” Davis says.

Davis helped them distinguish “what you really think” from “what you might think about.” Someone might complain to a chatbot after a fight or ask what would happen if they broke up, for example, but not feel that way once they’ve cooled down.

If you find these types of messages, you should ask your partner how they’re feeling, Davis suggests—not assume everything they typed is something they’ve been hiding from you. “A person can have private thoughts without being deceptive,” she says. “Couples need boundaries around private digital spaces just as they do around journals, therapy, or conversations with trusted friends.”

A chatbot also does something a journal doesn’t: It answers. But remember that it’s getting only one side of the story, says Shayce Johnston, a licensed mental health counselor in Gainesville, Fla., and the founder of Human AI Dynamics, which explores how people form emotional and relational bonds with AI. If your partner complains about you and the chatbot agrees, they may feel that someone else has confirmed you’re in the wrong. Johnston describes the reaction this way: “Even the AI agrees with me.” That doesn’t make it true.

How to set boundaries around AI in a relationship

Don’t assume you and your partner agree on what should stay private, says Tammy Nelson, a psychotherapist in Los Angeles and author of Open Monogamy: A Guide to Co-Creating Your Ideal Relationship Agreement. You might think nothing of opening their ChatGPT account; they might consider it the equivalent of reading their journal. Talk about that before you’re staring at something you wish you hadn’t seen.

“What parts are private?” Nelson asks. Keeping a password to yourself, for example, doesn’t automatically mean you’re concealing something that would hurt your partner. “I really do think that it’s important to revisit that conversation pretty often,” she says.

Reading the chats is only part of the issue. What’s OK to put into them? Johnston works with couples in which one person uses AI enthusiastically while the other has privacy, ethical, or environmental concerns. Your partner might be fine with you asking for date-night ideas but uncomfortable with you pasting in their texts or describing your sex life.

Grines suggests starting with a question: “Can you share something you’ve asked AI about our relationship?” You can also ask whether there are subjects they find easier to discuss with a chatbot than with you. The answers can help you get specific about what you’re both comfortable with: using AI to prepare for a difficult conversation, for example, or talking through an argument afterward. Discuss whether those exchanges will stay private or whether you’d like to share what came out of them.

If you’re tempted to skip the conversation and start scrolling through your partner’s chat history, Nelson suggests asking yourself why. Has something happened that makes you distrust them, or are you feeling anxious and hoping what you find will reassure you?

As Davis puts it: “What gets in the way of asking your partner directly?”

What to do after reading your partner’s AI chats

If you’ve read something upsetting, ask your partner what it meant before assuming you know. Davis encourages couples to wait until they’re calm enough to have that conversation. The person who used AI can explain what they were working through; the person who read the chats can explain what hurt.

Johnston wants couples to stop treating the chat history as a verdict on their relationship. Instead, she helps them understand “what the need was, what the fear is, and where the disconnection was that led to the conversation in the first place.” That means making room for both people’s feelings: You can be hurt by what your partner wrote, and they can be upset that you read it without permission.

There may still be a useful role for AI in the relationship. Grines has worked with couples who use their therapy notes to ask a chatbot for questions they can discuss together at home, for example. Johnston sometimes encourages clients to rehearse a difficult conversation with AI before having it with their partner.

“I don’t think AI is inherently anti-relationship,” Grines says. But she wants couples to consider whether it’s helping them talk to each other—or becoming the only place they’re willing to be honest. “AI can be a bridge into communication,” she says, “or it can be a place where communication goes to die.”

For Hall, finding out how her boyfriend used AI made her question conversations she’d once felt good about. Before meeting in person, they’d spent months messaging. He’d seemed warm over text, she says, but could be colder face-to-face. She’d wondered: “What am I doing wrong?”

His chat history offered a possible explanation. When they’d discussed serious or emotional subjects, she says, he’d pasted her messages into ChatGPT and asked it to help him respond. She remembers his instruction: “Placate her.”

“It’s horrifying,” she says now.

She still wonders whether he would have spoken so harshly about her to another person, or whether something about talking to AI encouraged him. “Would you have said all those things to a person in that way?” she asks.

After she left his house, he began texting her. She turned off her phone. When he later came to her home, she told him she’d read the chats. By then, she says, she felt there was little left to discuss: “I just read exactly how you feel.”

In the winter of 2015, Dr. Tom Chiller received a call from public-health officials in Britain.

They were panicking. A new fungus was causing devastating infections at a large London hospital. “They weren’t able to get rid of it,” says Chiller, who was then chief of the fungal-diseases branch at the U.S. Centers for Disease Control and Prevention (CDC). “They didn’t know what to do.”

The British officials said the fungus—a kind of yeast called Candida auris—appeared to be spreading from patient to patient. The officials said they were going to shut down parts of the hospital to curb its transmission. “That was just mind-boggling,” Chiller says.

At first he was more confused than alarmed. Candida is a kind of yeast that causes some of the most common fungal conditions, including thrush and vaginal yeast infections. Some species can cause severe illnesses, including bloodstream infections. But Chiller knew of no Candida species—indeed, no life-threatening fungus of any kind—that could spread so easily among people.

“I’ll never forget that call,” he says. “At first, I didn’t really believe it. Suddenly we have a yeast acting like a bacteria? It was weird.”

First discovered by doctors in 2009 in the ear of a patient in Japan, Candida auris behaves differently from most other fungi. It can survive at higher temperatures and in saltier environments, making nooks like a human ear, armpit, and groin ideal places to grow. It is exceptionally sticky and clings doggedly to people’s skin and hair follicles, and to surfaces—including slick ones, like hospital floors and beds, that are designed to repel germs. It is highly resistant to antifungal drugs, hard to kill with standard disinfectants, and can cause terrible, often deadly illnesses. Also, as British officials were starting to notice in 2015, it spreads easily through physical contact between people and via contaminated surfaces.

At the time of the call, though, much about Candida auris remained unknown. A few countries had reported a smattering of infections, but it hadn’t seemed like a big deal. No cases had yet been reported in the U.S. “It was a wake-up call,” Chiller says now. “We realized that, huh, maybe this little ear fungus isn’t just a little ear fungus anymore.”

In the decade since that phone call, that realization has cemented. When about 200 people—mostly doctors and researchers—attended a three-day conference about fungal diseases near Denver in September, Candida auris was the first topic on the agenda. To a nonscientist, the talks were dry, technical presentations on the pathogenesis and epidemiology of the disease, but to the attendees—and “almost everyone who works in mycology is here,” said Dr. Luis Ostrosky-Zeichner, an infectious-disease specialist at UTHealth Houston—they were red flags we should all be taking seriously.

Candida auris has rapidly gained ground since 2015. It has sickened tens of thousands of people in over 80 countries and six continents. The World Health Organization (WHO) has designated it one of the world’s highest-priority fungal threats. The CDC on Oct. 27 listed Candida auris as one of four top-priority drug-resistant pathogens that require "urgent and aggressive action." Thousands of cases are now reported in the U.S. every year. The CDC said this summer that the fungus had already infected more than 3,000 people this year in 27 states. Up to 60% of people who are infected die.

“In some U.S. states, it’s just endemic now. It’s there to stay,” Chiller says. 

Deadly fungal diseases were once considered very rare, but the proliferation of Candida auris points to a troubling trend: dangerous fungi are increasingly finding new opportunities to infect us, and human activity is spurring them on.

From the climate we’re warming to the medical treatments we use, we are creating conditions that allow fungal pathogens to thrive, infectious-disease experts say. Rising global temperatures, they say, likely led to the emergence of Candida auris and are driving the evolution of other fungal pathogens never seen before. Changing weather patterns are pushing some fungi to expand their geographic range, and the overuse of antifungals in medicine, agriculture, and livestock farming has driven them to develop resistance to these drugs.

“We are creating an environment that is favoring pathogenic fungi and drug resistance,” says Dr. Andrej Spec, a fungal-disease specialist at Washington University School of Medicine in St. Louis. “That means they are likely becoming better at infecting us, and also at evading our treatments. That’s a bad combination.”

Fungi are ubiquitous organisms. They live in, on, and all around us. Every day, we inhale thousands—if not millions—of fungal spores. There are an estimated 6 million species of fungi on the planet, but only about 300 of them cause diseases in people. “We are protected by our temperature and our immunity,” says Dr. Arturo Casadevall, chair of microbiology and immunology at the Johns Hopkins School of Public Health. The human body is too hot for most fungi to thrive, but as the earth warms, fungi are adapting.

Researchers think Candida auris, which likely originated in marine ecosystems, evolved a tolerance to salty conditions and high temperatures over time. The yeast can now survive at 107°F. 

Candida auris is not the only threat finding hot new hosts. A new fungal pathogen is disfiguring cats and people in South America, and certain molds, which once infected only plants, are now sickening people too. Spec published a report in 2021 describing the first case of a person infected by a mold that had previously been known to damage only trees. Since then, two more people in the U.S. have been infected, Spec says. “It’s gone from never causing human disease in the history of medicine to three new cases of it in the last five years,” he says.

In October, the CDC said that cases of a different mold—a brain-attacking variety—have jumped fourfold in the past two years. “This is a nasty pathogen,” Spec says. It infects even healthy people and causes brain abscesses that in up to 70% of cases are fatal.

“We’re seeing a lot of these molds that were once rare pathogens becoming more common,” Spec says. “A lot of us are leaning toward the idea that this is probably being driven by climate change.”

Spec and other doctors are working with public-health officials, patient advocates, and drug developers to try to stem the rise of threatening fungi. They’ve made some progress in recent years: raising awareness, doing more surveillance, and developing new drugs and tests, but the challenge is formidable.

As fungi develop mechanisms to better infect us, more people are becoming vulnerable to serious fungal diseases—because of advancements in medicine. Today, to fight autoimmune conditions and diseases like cancer, millions of people take drugs that suppress their immune systems. But immunocompromised people are at higher risk of contracting severe fungal infections. Thanks in part to those therapies, the growing population of immunocompromised people in the U.S. is now estimated to number at least 7 million.

“We have people who have immune conditions like multiple sclerosis, Crohn’s disease, and rheumatoid arthritis who might have died from these diseases in the past but aren’t dead thanks to these therapies. But they’re also immunosuppressed, so we have a bigger pool of people who are at risk,” Spec says.

More people are also being kept alive by invasive medical devices, such as heart-lung machines and ventilators, which can create pathways for germs including fungi to enter the body. “We’re making all this medical progress,” Casadevall says, “but that progress comes at a cost.” 

Ryan Zwick, a healthy 22-year-old, had just graduated from nursing school when COVID nearly struck him dead in December 2023. The virus, which research shows increases the risk of cardiovascular disease, severely damaged his heart.

Zwick spent a week in an intensive-care unit in Las Vegas before he was airlifted to a hospital in San Diego to receive more advanced care. He was intubated and sedated; his lungs, kidneys, and heart had all started to fail.

He was attached to a heart-lung machine, a life-support device that pumps a patient’s blood outside the body, via tubes placed into his sternum. “His chest was basically open for like a week,” his wife Emmy remembers.

Candida auris took advantage.

When Zwick finally woke up more than a month after being admitted to the hospital, doctors told him he had a severe Candida auris infection. The yeast, they said, likely sneaked into his body through the tubes in his chest. “It got into my bloodstream and kept causing a lot of issues throughout my body,” he says.

He was treated aggressively with antifungal drugs, which kept the infection under control. But the fungus lingered.

Zwick was discharged from the hospital in April 2024, but he returned to the emergency room a couple of weeks later because blisters had appeared at the incision site on his chest. He soon learned that the Candida auris infection was causing osteomyelitis, a serious and painful condition in which bone tissue becomes inflamed. “They took out a bunch of bone and stuff, and put me on more antifungals,” he says.

More than two years later, Zwick, who works as a nurse in New Hampshire, continues to receive weekly infusions of a potent antifungal drug to manage his infection. His doctors have warned him that he will likely have to take them for life. “It’s basically chronic now,” says Zwick, who still sometimes has swelling and blistering at the incision site.

Zwick worries that available antifungal drugs could one day lose their sting. Candida auris is highly resistant to many antifungals; a growing number of infections are “pan-resistant,” which means no medicines are effective against them. “I just hope these drugs keep working for me,” Zwick says.

When Candida auris first emerged in the U.S. a decade ago, it was a very rare and often severe disease whose victims were usually sick, elderly, and immunocompromised people in hospitals and nursing homes. But the yeast has been expanding its reach: not just infecting more people, but a broader range of them, and causing a wider variety of illnesses too.

“Ten years ago, we’d maybe see one Candida auris patient every few months,” says UTHealth’s Ostrosky-Zeichner. “Now, we have several cases per day in Houston.” Texas, New York, Nevada, Florida, and California are among the U.S. states with the highest number of cases.

More young people, like Zwick, and people who aren’t immunocompromised are getting infected, doctors say. The yeast is also starting to cause new types of hard-to-treat infections. Spec says that this year, for the first time, he treated a woman with a vaginal yeast infection caused by Candida auris. She had diabetes that was well-controlled and was otherwise healthy, says Spec.

The woman had come to see him after getting recurrent yeast infections that hadn’t responded to standard treatments, he says. She recovered only after being treated for several days with an IV antifungal drug more powerful than what is usually used to treat such infections, Spec says.

Vaginal yeast infections are very common, with an estimated 3 in 4 women having at least one in their lifetime. A class of antifungals known as azoles are typically used to treat such infections, either as a cream, suppository, or oral pill, but Candida auris is more than 90% resistant to azole drugs. “It’s no joke when you have to tell a woman that she has a vaginal yeast infection for which you usually take one pill and move on, but in her case, she needs to get on IV medication,” Spec says.

Doctors say Candida auris is also emerging as the cause of another common disease: urinary tract infections (UTIs), which roughly half of women will experience at least once. Doctors have known that Candida auris can cause UTIs in people with catheters, but they are now seeing cases of people with tough-to-treat infections who don’t have any medical devices or major health complications.

Public-health experts worry that the fungus could become as widespread as pathogens like MRSA: methicillin-resistant Staphylococcus aureus, a superbug bacteria.

“Initially, we tried to stomp it out, but we realized early on that Candida auris was here to stay. It was going to be more like MRSA,” says Chiller. “MRSA used to be hospital-only, and now it’s on every skin boil on the high school wrestling team.”

After Chiller got off the phone with his British counterparts in 2015, he went on a quest to better understand the fungus that he suspected would soon invade the U.S. He first wanted to know if Candida auris was already on U.S. soil but doctors had just missed it. Under his direction, the CDC sent out an alert to hospitals and researchers, asking them to test samples of unidentified fungal pathogens in their repositories going back decades. “We didn’t find Candida auris historically,” he says.

The CDC also collaborated with public-health officials in parts of Asia, Africa, and South America, where Candida auris cases had been detected. Together, they studied samples of the fungus in an attempt to understand how it emerged. They discovered something remarkable: at least three distinct strains of Candida auris appeared nearly simultaneously, over the course of a few years, but separately—in different corners of the globe. 

Many fungal-disease specialists and researchers now think climate change likely drove the yeast’s transformation from non-threatening environmental fungus to deadly pathogen. “It’s hard to explain the emergence of Candida auris simultaneously on all these continents and not include climate change as part of it. It just has to be. There’s no other good explanation,” says Dr. Peter Pappas, an infectious-disease doctor at the University of Alabama at Birmingham.

Fungi are sensitive to heat, but they are also very adaptable to rising temperatures. In laboratory experiments, researchers have put different fungi in incubators and, by steadily raising the temperature, have spawned fungi that are more tolerant to higher heat.

“It’s actually not that hard,” says Casadevall, who studies how fungi cause disease and was the first to publish the theory that global warming spurred Candida auris’ rise. “The slower you raise the temperature, the more the fungi can tolerate it. It doesn’t take a lot of mutations,” he says.

A study he published with colleagues last year showed how different microclimates within the same city can trigger changes in fungi. “We went to Baltimore and looked for fungi on the sidewalk in a cool part of town, where they had nice trees and it’s shaded, and then the same fungus in a warm part of town,” Casadevall says. “We found that even within one city, just two miles away, the fungi from the warm neighborhood grow at higher temperatures. So, it’s happening.”

Fungi are already a major threat to many plants, insects, and cold-blooded animals. Frogs everywhere are being wiped out by a fungal disease; rice and banana crops have been decimated by fungi; and millions of bats, which drop their body temperature when they hibernate, have recently died in North America because of a deadly fungus. Until now, however, most mammals have been protected by our high body temperatures.

The emergence of Candida auris is a “shot across the bow of humanity that these things can happen,” Casadevall says. “We can have an organism come out of nowhere, and begin causing disease.”

Many other fungi are changing in ways that are worrying and, in some cases, dumbfounding doctors. As temperatures rise and rainfall patterns shift, some are spreading to new places. The soil-dwelling fungus Histoplasma, which had historically been confined in the U.S. to central and southern regions, has been steadily moving northward, eastward, and westward. U.S. cases have increased twofold in the past decade. 

Valley fever, caused by inhaling microscopic fungal spores, is estimated to sicken up to 360,000 people in the U.S. yearly. The fungus was primarily found in the arid American Southwest until about a decade or two ago, when it began spreading to states like Washington, once considered too wet or cold for it.

Even fungal diseases considered mundane and easily treated, like ringworm, are evolving in alarming ways, doctors say. A new species of ringworm that can be resistant to all antifungal drugs has been spreading from the Indian subcontinent to the Middle East, Europe, and the U.S. in recent years. This new ringworm, which is highly contagious, causes chronic, inflamed, and itchy skin plaques all over the body.

“Think of athlete’s foot, but it’s now athlete’s body, and it’s untreatable,” Chiller says. He predicts this new disease, which experts think evolved in response to the overuse of over-the-counter antifungal medications, will become the predominant ringworm found globally in the next decade. 

In Brazil and South America, outbreaks of a fungus that causes a disfiguring and sometimes fatal skin disease have been sickening cats, dogs, and people. Like Candida auris, the pathogen has mysterious origins. The fungus was first identified as a threat in 1998 after an outbreak in Rio de Janeiro. First, cats started showing up to the city’s clinics very sick and covered with lesions. Then, people and dogs did too. Infectious-disease doctors identified the culprit of these illnesses as a type of Sporothrix fungus. Infected cats were spreading the disease to dogs and humans through scratches, bites, and even sneezes.

That explanation didn’t seem to make any sense at first, says Dallas Smith, a fungal-diseases scientist at CDC who tracks emerging pathogens including Sporothrix.

A species of Sporothrix fungus called Sporothrix schenckii had long been known to doctors and scientists. The pathogen causes what is often referred to as “rose gardener’s disease” because the fungus, which lives in the environment, typically infects people who work with dirt and plants. “Gardeners would get pricked by a rose thorn, and that would provide the opening for the fungus to enter,” Smith says.

The fungus was known to infect cats, but that was exceedingly uncommon. The disease itself was also very rare. At the largest hospital for infectious diseases in Rio de Janeiro, the Evandro Chagas National Institute of Infectious Diseases, doctors typically saw two to three cases a year before 1998, says Dr. Dayvison Freitas, an infectious-dermatology researcher at the hospital.

But seemingly out of nowhere, something incited the emergence of a more virulent Sporothrix species spread by cats and not plants. It isn’t clear what pushed it to evolve to so effectively infect cats. “Is it because of climate change or environmental change or some other pressures that we don’t understand?” Smith says.

Sporothrix brasiliensis was named as a separate species in 2007. Infections caused by the fungus can result in multiple lesions in people, sometimes all over the body and face. It almost always leaves lasting scars, which are often dark and raised, says Freitas.

In up to 10% of cases, usually involving elderly or immunocompromised people, the fungus can enter the bloodstream and cause destructive illnesses. “The fungus can affect any organ or system, including the bones, joints, lungs, throat, brain. It can cause a kind of meningitis,” Freitas says. “If this happens, it is very, very severe, and the death rate is high.”

Brazil has seen an explosion of the fungus in recent years. “Cats are spreading this disease among themselves, but also to humans at an alarmingly high rate,” Smith says.

From 1998 to 2001, fewer than 180 people, concentrated around Rio de Janeiro, fell sick with the disease. In recent years, thousands of people across the country are infected annually, Smith says.

The disease is now even infecting people in remote villages in the Amazon, Freitas says, and has emerged in other countries too. Cases of Sporothrix brasiliensis have been steadily sprouting up across South America in countries including Argentina, Paraguay, and Chile. Uruguay experienced its first outbreak of the disease in 2025, and Peru reported its first case this year, Smith says. “It’s just a matter of time before it ends up in the United States” and beyond, he says.

Sporothrix, says Chiller, is one of a growing number of fungi that are “dramatically changing our understanding of how we think fungi are supposed to act.”

At the Denver conference, a line of scientists followed Chiller wherever he went. Everyone there wanted to bend his ear. Chiller was decked out in his usual professional attire: a well-cut jacket with a colorful, bespoke fungi-print lining and a matching pocket square. (Chiller, whose grandfather was a tailor, has about 15 fungi-themed custom jackets.)

“In every generation, there tends to be a few people who are a force multiplier,” says Spec. “They change the field. In the case of mycology, the success that exists is often due to Tom Chiller.”

Chiller has been working for decades to draw the world’s attention to fungi’s gathering threat. He was the deputy director of the CDC’s fungal-diseases branch for about 10 years and its chief for another decade. Under his leadership, the department doubled in size to about 45 people and expanded its work to include surveillance of priority fungal diseases, including Candida auris, and research into emerging pathogens, as well as new treatments and diagnostic tools. 

He was instrumental in the development and widespread use of a cheap, simple, and accurate test, using just a pinprick of blood, for Cryptococcus—an environmental fungus that can cause meningitis. “It’s definitely saved tens of thousands of lives,” Chiller says. “I’m very proud of that.”

Chiller left the CDC last year after 25 years at the agency, months after Robert F. Kennedy Jr. was named head of the U.S. Department of Health and Human Services. Chiller says he had been growing increasingly disenchanted at the agency since COVID. “During the pandemic, it was turmoil for everybody. CDC took a big hit reputationally,” he says. Then Kennedy took the helm, and Chiller’s team was cut by about a quarter, he says. “We had to prioritize what we could do.” 

Chiller says he felt “handcuffed” by restrictions imposed on CDC staff in the spring of 2025. “They cut all our travel, they canceled all meetings. We didn’t really have budgets,” he recalls. “I thought to myself, If this is the future, it’s not for me.” Chiller is now chief medical officer at IMMY, a company that develops tests for fungal diseases. He’s also a board member of the nonprofit Global Action Fund for Fungal Infections and of MyCARE, a fungal-disease patient-advocacy organization. Now, he gets to do what he loves most: advocating for fungal-disease awareness.

In September, he attended a roundtable discussion about fungal diseases with Kennedy and other U.S. health officials. Chiller, who helped coordinate the meeting, says it was the first time in his career that he had been in a room with a U.S. Health Secretary to talk only about fungus. That felt like progress, he says.

Chiller knows just how critical it is for health leaders and professionals to be familiar with fungi. “Think Fungus” was the catchphrase of the CDC’s first Fungal Disease Awareness Week, which Chiller helped launch in 2017.  Doctors often miss fungal diseases because they fail to think of them, research shows.

Though the spread of fungi in a warming world may seem like an impossible foe, there is hope in the fact that diagnosing fungal infections early makes it much more likely that a patient will survive—and researchers, including Chiller, are working to help patients take advantage of that edge.

They’ve got a long way to go: a 2019 paper showed that almost half of some 270 patients in Arizona with valley fever—a fungal disease Chiller studied as a young doctor—weren’t diagnosed correctly for a month or more.

Justin John lived that nightmare. The 27-year-old software engineer from Arizona was wrongly diagnosed with COVID, the common cold, and irritable bowel syndrome before doctors realized—more than six months later—that he was sick with valley fever.

There were “lesions literally everywhere inside my body,” he says. After lumps caused by the fungus started appearing on his forehead and neck, doctors discovered that the fungus had eaten holes through parts of his spine and skull. He underwent two surgeries to insert a metal plate into his forehead, and replace a part of his vertebrae with a metal disc. “The vertebra was so dissolved, they couldn’t save any of it,” he says.

John says he was healthy, active, and had no underlying medical conditions before he got sick. “It’s in the dirt. You can get it anywhere at any time,” he says. “I could have gotten it when I was walking to Walmart.”

Blood tests are currently used to diagnose valley fever, but false negative results are common, causing many missed diagnoses. IMMY is developing a new rapid urine test for the disease that it says will be easier to administer and more accurate. “So many patients, even here in Arizona where this disease is endemic, get missed,” says Dr. Fariba Donovan, a valley fever specialist at the University of Arizona who treated John. “This test could really decrease that delay in diagnosis.”

These are steps in the right direction, but Chiller says we need to take greater strides if we want to win in the race against fungi. Many decades ago, after encountering very sick and dying valley fever patients, Chiller says he “learned a lot about how devastating and complex fungal diseases can be.” He’s still waiting for the rest of us to catch up.

Standing on your own two feet might be no problem. Lift one up to balance, though, and you might have a few concerns.

Fortunately, there are ways to get a leg up on better balance. “Balance is not a trait—it’s a skill,” says Dr. Cory Calendine, an orthopedic surgeon at the Bone and Joint Institute of Tennessee. One way to practice: Stand beside a sturdy counter, lift one foot, and work toward holding the position for 30 seconds before switching sides.

Staying upright can be surprisingly humbling. “It’s free, it’s simple, but it’s also honest, brutally honest,” Calendine says. “It’s a good assessment of where you are.”

Here’s why it’s worth practicing, plus how to get started.

The benefits of standing on one leg

You might not give your balance much thought, but it helps get you through the day—from stepping into the shower to climbing upstairs when you get home from work. Even walking down the sidewalk involves briefly supporting yourself on one foot with every step.

There’s a lot going on to keep you from tipping over: Your brain processes information from your eyes, inner ear, and sensory nerves, while your muscles help keep you steady. When you lift one foot, for example, the muscles along the outside of your standing hip help keep your pelvis level. “All of these things are being coordinated for you to stand in one position without falling,” Calendine says.

Your balance can improve with practice: A review of 13 studies found that single-leg balance training improved balance performance in healthy adults. Calendine suggests working toward 30 seconds on each side, starting with however long you can safely manage.

Still, preventing falls takes more than good balance—you also need strong muscles to support you. A large Cochrane review found that exercise programs that focused on balance in addition to everyday movements, like getting up from a chair, reduced the rate of falls in older adults by about a quarter. While standing on one leg is a good start, it shouldn’t be the only exercise you do. “Balance is the front door, but strength is the whole house,” Calendine says.

How to stand on one leg to improve your balance

Find a sturdy counter you can hold onto, says Kevin Pozzi, an assistant professor in the doctor of physical therapy program at Johnson & Wales University in Providence, R.I. Check that the floor isn’t slippery, and give your footwear some thought: “Sneakers would be ideal,” he says, as long as “they’re tied well and they fit.”

If you’ve fallen before or had a significant injury or surgery involving your legs, hips, or spine, talk to a health professional before getting started. Pozzi also recommends getting help if you can’t hold the position for 10 seconds. A physical therapist can assess your balance and suggest a routine that’s safe for you.

Otherwise, start with your hands on the counter, stand tall, and lift one foot off the floor. Keep your core engaged and avoid slumping over, Pozzi advises. Bending your lifted knee so your foot is slightly behind you often feels most comfortable, though you can also lift it in front if there’s room. “See how long you can hold first while holding on,” he says. 

If that feels easy, you can start easing up on your hands. “Maybe you go down to one hand,” he says. “Then lighten your grip even with that one hand so that you’re really not relying on it quite so much.” Keep it close enough to grab the counter if you need to.

Work toward 30 seconds, then switch legs. One side might feel easier than the other, especially if you’ve had an injury. “They’re not always the same,” Pozzi says. Once you can comfortably manage 30 seconds on each side, try repeating it a few times throughout the day.

And don’t expect to be perfectly still. “It’s normal to have a little bit of wobbling,” he says. You might feel your ankle moving or notice small shifts at your knee and hip as you try to stay upright. That doesn’t mean you’re doing it wrong. But if you’re wobbling so much that you keep grabbing the counter or putting your foot down, hold on and make it easier.

Don’t expect immediate results; this balance exercise takes time to work. Pozzi says people may start noticing changes after four to six weeks of consistent practice, including being able to hold the position longer. “Getting their socks and shoes on might be a little easier,” he says.

How to make balance exercises a daily habit

Calendine works on his balance while his coffee brews, both at home and at work, giving each leg a turn. “Nobody even knows I’m doing it,” he says. “They’re standing beside me, but you can kind of hide it, which is nice.”

Dr. Vonda Wright, an orthopedic surgeon in Orlando, practices so often that she sometimes catches herself standing on one leg while giving a speech. She also asks rooms full of executives to try it—and watches them struggle. “It may be one of the only things they fail at,” she says.

To make practicing easier to remember, she suggests pairing it with something you already do. Once you feel steady enough, try standing on one leg while brushing your teeth or taking a phone call beside your desk, with a sturdy surface nearby. “You’ve got to brush your teeth anyway,” she says. “Do it on one leg.”

When holding the position for 30 seconds feels easy, you can gradually increase the challenge. Wright suggests placing a folded towel under your standing foot, which makes the surface less stable. Another option is moving your arms while you balance. Change one thing at a time, with support within reach.

Think you’ve gotten pretty good at the whole thing? Try briefly closing your eyes; without being able to see, staying upright gets trickier. “Always be near something you can grab onto,” Wright says. If you lose your balance, put your foot down and start again. “We’re trying to make this a lifestyle,” she says, “not a workout regimen.”

Women are speaking more openly about periods, pregnancy, perimenopause, and menopause, bringing once-taboo topics into public conversation. Clinicians and health systems need to now connect these experiences with what the science is telling us about how they influence a woman’s cardiovascular health throughout her life.

A woman may see a gynecologist for her irregular periods, a therapist for her depression, and a primary care doctor or cardiologist for her high blood pressure. Each clinician may focus on an important concern. But what is often missing is a shared understanding of how those concerns fit together and what that means for her lifelong cardiovascular health. 

A narrow lens has too often been applied to women’s health, defining it as care of reproductive organs and pregnancy. Reproductive health is essential to a woman’s well-being, but women’s health is much broader. We now know that menstrual patterns, pregnancy, and menopause can provide important information about cardiovascular health. Our approach to care should reflect this.

These missed connections matter because cardiovascular disease is the greatest threat to women’s health today. Approximately 1 in 3 deaths in women are due to cardiovascular disease every year. Yet fewer than half of women knew that heart disease was the leading cause of death for women, according to a 2019 survey performed by the American Heart Association. 

As a preventive cardiologist and epidemiologist, I study how women’s life events shape cardiovascular disease risk. We now know that unique signals of cardiovascular risk in women can be identified years and decades before heart disease develops. The challenge is making sure that this information changes the care women receive.

This is what led the American Heart Association to bring together the American Academy of Pediatrics, American College of Obstetricians and Gynecologists, and Society for Maternal-Fetal Medicine. Our three-part series, published today in Circulation, establishes a new framework for cardiovascular health in girls and women. The papers and accompanying videos introduce the new Female Life Stage tool, provide clinical guidance, and outline how health systems can deliver coordinated care throughout life.   

This framework gives clinicians a shared approach to cardiovascular disease prevention across specialties, interconnected areas of health, and life stages.

What one clinician learns should inform the care a woman receives in different settings and from different clinicians. For example, pregnancy can act as a natural stress test, revealing cardiovascular risks that may otherwise go unrecognized. A history of preeclampsia should inform cardiovascular preventive care long after delivery. The 2026 Cardiovascular Kidney Metabolic Syndrome Guideline now explicitly recognizes pregnancy complications, as well as premature menopause, as one of the factors that can inform personalized prevention.

Menstrual cycle patterns can also provide information relevant to cardiovascular care. A first period before age 10, irregular menstrual cycles, or menopause at a younger age can each serve as signals of higher cardiovascular risk. In a study of more than 10,000 women that my colleagues and I recently published, menopause occurring naturally before age 40 was associated with an approximately 40% higher lifetime risk of coronary heart disease. 

Mental health is also linked to hormonal and cardiovascular health. Premenstrual syndrome (PMS) can frequently disrupt sleep, physical activity, and eating patterns, which are relevant to cardiovascular health. These symptoms are common, but being common does not make them inconsequential. Mood symptoms during the menopause transition likewise deserve assessment and treatment as part of comprehensive care. 

A woman and her care team need to anticipate that her health needs will change from adolescence through older adulthood. The framework defines four Female Life Stages: the transition around the first period, the years of ovarian cycling (including pregnancy), perimenopause, and postmenopause. It gives clinicians and patients a shared language for recognizing changing health needs so everyone can know what to expect, identifying cardiovascular risk earlier, and guiding prevention across a lifetime. 

Recognizing perimenopause as a distinct life stage acknowledges that its symptoms can disrupt daily life, persist for years, and deserve treatment. Hormone and nonhormonal treatments can help, with decisions guided by symptoms, age, cardiovascular and cancer history, and a woman’s preferences. The same visit offers an opportunity to assess cardiovascular disease risk and address changes in cholesterol and cardiometabolic health. 

Women may spend nearly 40% of their life in the postmenopause stage. Yet conversations of hormonal health and their enduring impact often end with the last period. Hormonal health history should continue to inform cardiovascular care. 

But documenting information in the medical record will not be enough. We also need to change how care is delivered.

An instructive historical example can be drawn from Vienna. In 1991, an art exhibition documented the daily lives of eight girls and women, including an eight-year-old, a student, a nurse, and a retiree. This resulted in the city incorporating women’s everyday needs into urban planning, including street lighting on walking routes for women’s safety.

Health care should apply this principle; women’s experiences should shape how care is organized and delivered. But this redesign must be paired with structural change that addresses the barriers, bias, and discrimination that contribute to symptoms being dismissed, delays in care, and unequal access to health care and treatment for women. 

A shared framework—like the one we developed—can support implementation of existing evidence, but we also need better evidence for women. In 1993, the NIH Revitalization Act made women’s inclusion in NIH-funded clinical research a requirement. Yet underrepresentation in research persists. A 2025 systematic review of cardiovascular trials registered from 2017 through 2023 found that women comprised 41% of participants but only 22% in trials studying acute coronary syndromes, including heart attacks. 

Women’s health research also remains underfunded, though there may be some recent signs of progress. In October, President Trump signed an executive order to create a new division for women’s health in the National Institutes of Health, but no funding has been allocated at this time.  

These efforts are part of a larger movement that builds on decades of public advocacy for women’s health. Since its launch in 2004, the American Heart Association’s Go Red for Women campaign has helped bring women’s cardiovascular health into public view. Melinda French Gates’ investments through Pivotal are directing resources toward understudied areas in women’s health. Katie Couric and Dawn Porter’s forthcoming documentary “HORMONAL!” will add to this momentum by sharing women’s experiences. 

Girls and women represent half the population, and every clinician, every specialty, and every health system has a role to play in their health. Women can do much to protect their health, but they should not have to connect the dots in their care alone. 

Moderna and Merck reported on Oct. 22 that a customized cancer vaccine for people with late-stage melanoma can reduce the risk of cancer recurrence or death over two years by 42% compared to current treatment.

The results will be presented at the European Society of Medical Oncology meeting in Madrid on Oct. 24.

The study involved more than 1,130 people with Stage 2B to Stage 4 melanoma, all of whom had their tumors surgically removed. Some were then randomly assigned to have a cancer vaccine custom-made after their tumors had been genetically sequenced. They received that vaccine, called intismeran, once every three weeks for up to nine doses, along with Keytruda, a checkpoint inhibitor, every six weeks for up to nine cycles, for about a year. Others were randomly assigned to receive a placebo vaccine and Keytruda.

Intismeran, developed jointly by Moderna and Merck, represents a new way to harness the immune system in cancer, by training immune cells to recognize 34 specific proteins on tumor cells. The mRNA coding for these proteins, or antigens, are encased in a lipid particle in a similar way to Moderna’s COVID vaccine, which used mRNA from the COVID virus’ spike protein. Using this mRNA approach, once cells start making the foreign proteins coded for by the mRNA, the immune system sees them as intruders and mounts a response against them—and the latest data show that the approach works not just against viral proteins but also against those found on tumors.

Keytruda contributes a key part of the response by removing the brakes that keep immune cells from recognizing and attacking tumor cells because they originate from normal "self" cells.

“I was surprised by the fact that the results replicated the Phase 2 [study] so closely,” says Dr. David Berman, chief development officer at Moderna, referring to an earlier stage study the companies released in June that the combination lowered the risk of cancer returning or death by 49% over five years. That study also reported that the therapy lowered the risk of the cancer spreading to other sites by 59% compared to the checkpoint inhibitor alone. “This Phase 3 [study] included a much broader population, so the hypothesis was that the treatment effect would be harder to see. There was a lot of suspicion going in that these results would not be as good as those in the Phase 2. But the fact that they reproduced almost exactly what we saw initially in the Phase 2 blew my mind.”

The companies report that the effect seems to start six months into the therapy—an important insight in understanding how immune-based approaches may work in cancer. “We think it’s because the immune system takes time to be activated,” says Berman. That includes making sure that immune cells like T cells, which are critical to recognizing and controlling cancer, have time to learn to detect tumors. Berman says these results could also help to explain why only about 30% of cancer patients respond to the checkpoint inhibitors, a powerful new tool in cancer that allows immune cells to see tumors rather than thinking they are "self" cells and therefore not foreign. “This shows us that in a significant percentage of patients, the checkpoint inhibitors are not doing anything because the immune system hasn’t even been educated to recognize the cancer cells,” he says of the potential role that the mRNA-based intismeran may play. “That’s where we now need to focus—on how to better educate the immune system. It’s a big leap, a big piece of information, that there is now another way to educate the immune system to recognize cancer.”

Data on overall survival of people on the combination therapy isn’t available yet.

Moderna and Merck are studying the intismeran-Keytruda pairing in other cancer types in nine other studies, such as pancreatic and gastric cancer, as well as in three late-stage trials of non-small cell lung cancer. They are also exploring the role of using intismeran alone in an early study in lung cancer.

Traditionally, personalized therapies have not been practical as medical treatment because of their high cost and long timeline to develop. But Berman is confident that the bespoke process of making an individualized mRNA cancer vaccine for each patient is both scalable and potentially affordable. “We have scaled down the technical footprint and have plans to scale up [the program] to look at different tumors,” he says. “The nice thing about the [mRNA] system is that it’s purely enzymatic, so no cell cultures need to be grown.” Another advantage of using mRNA is its speed—scientists at Moderna can develop a customized vaccine based on a patient’s tumor within weeks—critical for any patient with cancer.

Correction, Oct. 23

The original version of this story misstated the length of time of a study that showed a 49% reduction in recurrence of cancer. It was over five years, not over a year.