Most people breathe fungal spores daily without getting sick

Fungi make people sick when they invade and survive in otherwise healthy human tissue

We breathe in airborne spores frequently, but they often don't make us sick. This video details how certain concerning fungal changes can occur and discusses the role of mycologists—scientists who study fungi—in helping to improve human health.

Cryptococcus neoformans, a growing threat, causes infections in the brain and lungs

This inhalable, microscopic pathogen is found worldwide. It rarely causes illness, but it can take root in those with compromised immune systems, including people with advanced HIV/AIDS. Symptoms of cryptococcal infection—such as a stiff neck, vomiting, and confusion—can begin weeks or months after breathing in spores, though sometimes symptoms won’t appear for years. There are no known cases of transmission between people or between people and animals.

19 fungal pathogens are of key concern to world health officials

In 2022, this global health body issued its first-ever list of top fungal threats to human health. It said fungal threats are spreading and occurring more frequently. The WHO’s list included 19 fungal pathogens to watch, and said that the most dangerous ones to public health are Cryptococcus neoformans, Aspergillus fumigatus, Candida albicans, and Candida auris. There are only a handful of classes of medication currently available to combat fungal pathogens, with few others in the pipeline even though antimicrobial resistance is growing.

Fungal diseases cost the US around $19B annually

Estimates derived from health insurance claims, death certificates, and hospitalization data suggest that fungus is a significant medical issue. Each year, fungal diseases kill some 7,300 people—roughly the same number of deaths attributed to motor vehicles striking pedestrians. Around 130,000 people are hospitalized with fungal diseases, and the total national cost from fungal diseases is estimated to be about $19B—a figure that roughly matches Jamaica's entire gross domestic product.

Black mold isn’t more worrisome than other colors of mold

Black mold typically refers to Stachybotrys chartarum, a mold that commonly appears in damp or water-damaged areas of the home. Black mold—and other molds—won’t typically make otherwise healthy people ill, and all molds should be treated the same with respect to health risks and removal. If you have mold allergies, mold can cause an allergic response, and it can trigger asthma attacks for people with asthma. If you have a compromised immune system, then black mold exposure can also cause a fungal infection in your airways or elsewhere in the body.

Mapping the spread of a dangerous fungus growing in US healthcare facilities

Explore the data showing how the fungus C. auris has spread in the US, with more than 10,000 reported cases since 2016. Recommended steps to prevent infections and limit their spread have been successful in some areas, but infection control remains complicated because the fungus is often now multidrug-resistant.

Particles found in Martian air pose significant risks to human lungs

Ultrafine dust, just 3 micrometers wide, is small enough to bypass lung defenses and enter the bloodstream, where its highly reactive chemicals can cause thyroid disease. Silica in the dust can also cause silicosis, a chronic and incurable lung disease.

Flu spreads through droplets in the air and on surfaces

Influenza passes mainly through tiny droplets released when sick people cough, sneeze or talk. The virus can also survive briefly on surfaces, allowing it to spread when others touch contaminated objects.

Natural toxins produced on plants or consumed by animals may cause food poisoning

When humans eat plants with certain natural toxins on them—including a family of toxins called aflatoxins that fungi produce on crops like peanuts and corn— they can become ill with food poisoning. Toxins can still harm humans even if animals or plants appear fine to the human eye. The World Health Organization advises that we should throw away moldy or discolored foods, refrain from eating wild plants or mushrooms that aren’t definitively nonpoisonous, and remember that just because something is “natural” it’s not always safe to eat.

Amish kids have far fewer allergies than the general population

Only about 7% of Amish children in a northern Indiana community have tested positive for common allergens in routine skin prick tests, whereas half of the general US population tests positive for them. Asthma is also extremely uncommon among the Amish, even when compared with other farming communities. Researchers are interested in exploring if approaches like exposing kids across the general population to Amish farm dust might stave off some allergies.

Research suggests the cleanliness of the ISS may make astronauts unhealthy

The International Space Station's sterile conditions deprive astronauts of the opportunity to strengthen their immune systems through microbial exposure. To address this problem, future missions may use probiotic-based cleaners and foster diverse microbes in space habitats.

1 in 6 Americans get food poisoning each year

The US federal government estimates there are about 48 million cases of foodborne illness in the country annually, resulting in as many as 3,000 deaths and 128,000 hospitalizations. Food poisoning puts those with weakened immune systems, the elderly, pregnant people, and young children at particularly high risk. This chart of common disease-causing pathogens highlights common threats and details about them, including likely food sources.

Billion-year-old Arctic fossils suggest Earth had fungi far earlier than previously thought

Named Ourasphaira giraldae, this new species of fungus, reported in 2019, was found in the Grassy Bay Formation in the Canadian Arctic. It pushed the fossil record of fungi back by about half a billion years since the oldest previously recognized fungi fossils came from the Rhynie chert, a Scottish site that dates back roughly 400 million years. This fungal discovery also suggests that fungi may have occurred on land much earlier than plants, raising questions about what ancient fungi used for nourishment.

Watch an expert's take on the rare disease hantavirus—and why it's not of great concern to the general population

This rare zoonotic disease, transmitted to humans primarily through infected rodent droppings, urine, or saliva, is rarely spread between people. The disease was of particular concern in spring 2026, when an outbreak occurred on a 150-person cruise ship, prompting a flurry of action, including contact tracing for passengers in their home countries. The disease can be fatal. But early care—primarily oxygen support—can help patients survive.

Tornadoes can cause significant air pollution and diminish air quality

Asbestos, a hazardous material that can cause lung cancer, is commonly found in buildings constructed before 1980. Tornadoes that damage such buildings can release asbestos into the air, along with other toxic pollutants and dust as materials are lifted. Individuals, particularly those with asthma or other chronic lung diseases, are encouraged to wear masks after a tornado.

Inhalers dilate airways and reduce inflammation

People with asthma suffer from constricted airways in their lungs, whether from muscle pressure, mucus buildup, or inflammation. Inhalers help people breathe medicine directly into their lungs to immediately relieve these symptoms.

Human-to-human transmission of hantavirus remains extremely rare, so the 2026 hantavirus cruise ship outbreak doesn't mean we're facing a COVID-style pandemic risk.

About 95% of people are naturally immune to leprosy

Contracting it requires prolonged contact with someone with the disease, meaning you'd have to be living with them. You cannot get leprosy from hugging someone with leprosy or sitting next to them. It's not known to pass from mother to fetus. The risk of transmission from armadillos is also likely low, but people should avoid touching wild animals for general safety.

Approximately 70% of all polio infections in children are asymptomatic

Most polio infections are asymptomatic or appear with only flu-like symptoms. Infected individuals can still shed the virus in their stool and mucus for days or weeks

Roughly 15 of every 1,000 people in the US have smell disorders

Anosmia is a lack of a sense of smell. It can be present at birth, related to diseases including Parkinson's, Alzheimer's, and COVID-19, or have unknown causes.

Between 10 million and 50 million people in the US develop rashes from poison ivy, poison sumac, and poison oak each year.

Ticks are extremely hard to kill

These arachnids can transmit more than a dozen diseases to humans, and they're very resilient: Some can survive extreme heat and cold, live for years without a blood meal, and even survive multiple days underwater.

Artificial sweeteners are considered safe for most people

These sugar substitutes are generally preferred because they are sweeter than sugar and can be used in smaller amounts while still getting a sugary taste. Though generally regarded as safe, sugar substitutes can cause flare-ups for individuals with bowel disease, and researchers are investigating how these substances affect gut microbiome health. Aspartame can also cause health issues for individuals with a rare genetic disease called phenylketonuria.

The use of fungi to detoxify land and water—a process known as mycoremediation—has been used to clean up natural resources affected by the 2025 California wildfires.

Microplastics are entering human food chains through fertilized farmland

Microplastics from sewage sludge used as fertilizer contaminate agricultural soil and eventually enter our bodies through the food supply of carrots, wheat, and other foodstuffs. In Europe, farmland may absorb up to 710 trillion microplastic particles yearly.

Misleading measurements and fear-based reporting often exaggerate radiation risks

Daily exposure to radioactivity is common but occurs in low doses outside of locations near nuclear accidents like Chernobyl and Fukushima. Researchers have detected radiation in tuna, bananas, and the human body due to increasing instrumental sensitivity, not rising concentrations.

Swimmer's ear is not contagious

Though a lot of people may have symptoms of swimmer's ear at the same time at the same pool, that's because they are all swimming and the moisture is remaining in their ears—not because they are passing this bacterial or fungal-caused infection to each other. People of any age swimming in a pool, lake, or other body of water are all at risk, though children are considered particularly vulnerable.

Doctors differentiate between a phobia and fear by asking patients whether their fear interferes with their day-to-day activities.

Which organs can you live without?

While there are some organs (such as the heart) that people simply can’t live without, there are other organs that can be removed without a huge impact. Patients who have their appendix removed, for example, experience no changes to their daily...

Hookworm infection, though risky, may help fight certain autoimmune conditions by tamping down the immune system's inflammatory response.

Bone marrow (soft tissue found inside certain bones) generates roughly 500 billion new blood cells each day

Volcanic activity may have triggered the Black Death by spewing gases that led to crop failures in Europe, thus forcing the import of grain ships with plague-infested fleas.

Tattoos remain visible on your skin thanks to immune cells called macrophages

See images of medical cases of firework injuries shared on this 'Instagram for doctors.' (Warning: Graphic content)

Astronauts have repaired genetic damage in space using CRISPR—a molecular tool that can make precise changes to DNA and is used in single-celled organisms to attack invasive viruses.

Explore what it's like inside a patient isolation unit, used in situations such as treating a patient or suspected patient with Ebola.

The American cockroach is actually from Africa, an apparent hitchhiker aboard ships carrying enslaved people, with evidence suggesting the bug may have arrived in the New World as early as the 1600s.

Listen to an in-depth conversation on the links between Parkinson's disease and herbicide exposure and the challenging pace of scientific investigation.

At the beginning of the 20th century, a group of young men ate standard American food—replete with food additives like borax and formaldehyde—as part of government research to better understand food safety.

Studies suggest when you sleep is as important as how much you get, and syncing with your circadian rhythms may lead to less fatigue and improved long-term health outcomes

Planarian flatworms are small, aquatic worms with exceptional regenerative capabilities. When cut, the worms can regenerate multiple bodies in a matter of weeks.

Budweiser stores yeast derived from the original 1800s strain in a secret bunker, which only the Head of Yeast Management can access—not even the CEO

Alzheimer's can lead to brain shrinkage, with an average of around 2% of volume reduction per year

In 1963, a basement renovation in Turkey revealed a passageway to a hidden, multilevel underground city that once housed as many as 20,000 people

Scientists can determine Earth's past climate conditions by analyzing air trapped in microscopic bubbles within ice cores—columns of compressed snow layers that build up over hundreds of thousands of years.

In 1939, baseball star Lou Gehrig delivered his inspirational 'Luckiest Man' speech after retiring due to the health condition that now bears his name.

Some Pokémon have been named after real and fictional organisms, while some real-world species have been named after Pokémon, such as Chilicola charizard and Binburrum zapdos.

While atoms are normally made of protons, neutrons, and electrons, exotic ones have been built with antimatter—alternate versions of normal matter that live for fractions of a second and are about a billion times as rare.

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US intelligence allegedly pursued more than 600 schemes to assassinate Cuban revolutionary Fidel Castro.