Infectious Dose

A fungus appears in hospitals on different continents. You assume it started somewhere and spread. Then scientists sequence it and discover that the story is much stranger.

This week on Infectious Dose, we're exploring the strange emergence of Candida auris, now taxonomically known as Candidozyma auris. We trace the organism from its description in Japan to the discovery of genetically distinct lineages emerging in different parts of the world, and ask a question scientists still haven't completely answered: why did this fungus seemingly become a human pathogen in several places within such a short period of time?

Along the way, we'll explore why C. auris is so well-suited to healthcare environments, how people can carry it without becoming sick, why it can persist on surfaces and resist ordinary infection-control measures, and what happens when it also becomes resistant to the limited antifungal drugs available to treat invasive infections. And ahead of Fungal Disease Awareness Week, we'll look at the larger lesson of the C. auris story: fungi deserve a much bigger place in how we think about emerging infectious disease.

Full annotated citations and additional resources for this episode are available in the companion blog post at InfectiousDose.com.

Put on a coat. Dry your hair. Don’t sit on that toilet seat. Green snot means antibiotics. And if food hits the floor, you have five seconds.

But how much of the infectious-disease wisdom we inherited from our parents is actually true?

In this episode of Infectious Dose, we put some of the classics under the microscope: whether being cold can really make you sick, what green mucus actually tells us, why fever isn’t a good measure of how sick someone is, whether public toilet seats deserve their reputation, what the five-second rule gets wrong, and why a case of head lice does not require decontaminating your entire house.

It turns out many of these myths started with perfectly reasonable observations. The problem came when generations of parental anxiety tried to explain the biology.

Mom wasn’t necessarily wrong about what she saw. She was just wrong about the rhinovirus waiting for you on the porch.

Want to dig into the science behind this episode? You’ll find the full companion blog post, including annotated citations and links to the research, at InfectiousDose.com. While you’re there, you can also sign up for Field Notes, the free Infectious Dose newsletter, for more infectious-disease stories, outbreak updates, and curiosities between episodes.

In this Outbreak Watch, we return to the outbreaks and signals we’ve been tracking...and several have changed. 

New genomic evidence is revealing the hidden early months of the DRC’s Bundibugyo Ebola outbreak, while Uganda has successfully ended transmission across the border. New World screwworm is worsening in Sonora as cattle imports into Arizona resume, and COVID-19 is climbing again across the South amid changes to how CDC categorizes and displays wastewater activity. We also check in on measles, Cyclospora, H5 avian influenza, Vibrio vulnificus, mpox, Oropouche, and other signals on the board—and close the loop on the quarantined riverboat near Kinshasa.

Full citations in companion blog post at Infectious Dose.

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Somebody's roommate's cousin definitely knows the person this happened to.

This month on Outbreak After Dark, pull up a chair for an evening of infectious-disease urban legends. Heather investigates the infamous “Welcome to the World of AIDS” story and infected-needle scares, whether you can really get crabs from a toilet seat, and the long-running warning about fatal leptospirosis from rat urine on soda cans.

Each story gets a Campfire Verdict as we separate genuine biology from folklore and ask what happens when something that could happen gets transformed into a story people swear happened.

Then Heather and her unusually quiet cardboard cohost, CK, play Construct a Contagion, building an infectious-disease urban legend from scratch and testing their creation against real microbiology.

Because possible, plausible, and proven are three very different things.

Citations and resources can be found in the companion blog post at Infectious Dose.

What changes when the sun goes down?

In the final episode of From Sunrise to Starlight, we're heading down a summer trail as dusk gives way to darkness, following the microbes—and the vectors and hosts that carry them—into the night.

We'll explore why different mosquitoes keep different schedules, how ticks find hosts, what wildlife encounters actually mean for zoonotic disease risk, and how artificial light can alter nighttime ecology. Then we'll emerge from the woods beside a dark lake, turn off the flashlight, and look up.

Because infectious-disease risk isn't simply about which pathogens are present. It's about encounters: where they happen, when they happen, and how microbes, vectors, hosts, and human behavior come together.

Night Hike: Following Microbes Into the Dark closes our August journey from the first light of morning to a lake beneath the stars.

All citations in the companion blog post at Infectious Dose. 

It’s afternoon in our journey From Sunrise to Starlight, and we’re spreading out the picnic blanket.

This week, we’re following the hidden microbial pathways running through a summer meal. From farms and kitchens to the cooler, the blanket, and eventually us. We’ll explore how foodborne pathogens such as Salmonella, Listeria, Cyclospora, and norovirus reach our food, what happens as the cooler warms, and how hands, utensils, flies, ants, and even a shared bag of chips can turn a picnic into a transmission network.

Plus: Does the five-second rule work? Can ants actually contaminate your food? Is mayonnaise really the problem with potato salad? And when the picnic is over, which leftovers should come home?

Pull up a corner of the blanket. Lunch is served.

See companion blog post for citations.

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The guy in the white house signed a new executive order changing federal childhood vaccine policy. So what actually changed and what does it mean for families?

In this bonus Booster Dose episode, Heather separates the executive order itself from claims made during its announcement and break down what we know right now.

She covers the new categories of childhood vaccine recommendations; the proposal to separate MMR into individual measles, mumps, and rubella vaccines; the directive calling for childhood immunizations to be administered at separate medical visits “to the maximum extent feasible”; potential effects on vaccine access and insurance coverage; what states can—and don’t have to—do in response; and what parents should know about upcoming vaccination appointments.

She also addresses claims he made about MMR safety, the amount of vaccine children receive, giving multiple vaccines at once, and autism and point you toward previous Vaccine Safety Files episodes for deeper dives into the evidence.

This policy is still developing. This episode reflects what we know as of August 10, 2026.

Relevant Vaccine Safety Episodes:

Measles and MMR

Too Many Too Soon?

Vaccines & Autism

 

Ebola nears 4,000 confirmed cases in the Democratic Republic of the Congo, New World screwworm continues circulating in Texas, and the U.S. cyclosporiasis outbreak is expanding.

In this Outbreak Watch, we look at what has changed and what the evidence actually tells us, including why there’s currently no evidence that mutation explains the severity of the Ebola outbreak and why wildlife surveillance may be crucial to understanding screwworm transmission.

Then we zoom out for Global Signals and Surveillance Milestones: Chile’s nationwide hantavirus response, H5 avian influenza, Oropouche virus, a 30-year measles high in the United States, and rising Hansen’s disease cases in Florida.

All Citations in companion blog post at the website.

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A summer morning at the lake is about swimming, skipping stones, dragonflies, and family memories, but it's also the perfect opportunity to explore one of nature's most fascinating invisible ecosystems.

In this episode, we're diving beneath the surface of freshwater lakes to discover how microbes respond to changing environmental conditions throughout the day. We'll discuss:

• Why swimmer's itch is caused by a confused bird parasite—not dirty water
• How cyanobacterial (blue-green algae) blooms develop and why not all blooms are toxic
• The real story behind Naegleria fowleri, the so-called "brain-eating amoeba," and why infections remain extraordinarily rare
• How sunlight, temperature, wind, and wildlife shape lake microbial communities
• How public health agencies monitor recreational waters
• The growing role of citizen science in protecting lakes and rivers

Whether you're a swimmer, paddler, angler, pet owner, or simply someone who loves spending time outdoors, this episode will give you a new appreciation for the remarkable—and mostly unseen—life beneath the water's surface.

All citations and resources in the companion blog post on the website.

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Medicine. Contraband. Comfort.

Step inside a hidden 1920s speakeasy where the jazz is live, the whiskey is illegal, and one of the most surprising chapters in medical history unfolds.

During Prohibition, physicians could legally prescribe medicinal whiskey for illnesses ranging from pneumonia and influenza to pain and "nervous exhaustion." At the same time, bootleggers, pharmacists, lawmakers, and patients were all navigating a confusing world where the same bottle could be medicine, commodity, or contraband.

In this immersive Outbreak After Dark episode, Heather and Kate explore:

• Why doctors prescribed medicinal whiskey before antibiotics
• How Prohibition reshaped medical practice
• Patent medicines and the blurred line between treatment and marketing
• Industrial alcohol and the tragic consequences of denaturing
• What these stories reveal about medicine, evidence, and human behavior

Join us for an evening of jazz, secret passwords, and one of the most unusual intersections of infectious disease and American history.

Full citations and more at the website.

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