Infectious Dose

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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For much of history, entering a hospital could be one of the most dangerous decisions a person could make. Patients survived injuries and operations only to die from infections acquired in the very places meant to heal them.

In this final episode of our Turning Points in Infectious Disease series, we explore the revolution that transformed hospitals from centers of disease transmission into institutions designed to prevent infection. Follow the stories of Ignaz Semmelweis, Louis Pasteur, Joseph Lister, and Florence Nightingale as medicine gradually uncovered the invisible world of microbes and reshaped healthcare around one revolutionary idea: the safest infection is the one that never happens.

We'll also explore why healthcare-associated infections still occur today and what this history teaches us about the ongoing challenge of translating scientific evidence into everyday practice.

Check out the companion blog post at the website for full, annotated citations , historical images, and more. And subscribe to the free weekly newsletter, Field Notes, to continue the conversation, get updates on outbreaks and the infectious disease signals Heather is paying attention to, and get a peek behind the scenes.

In this edition of Outbreak Watch, we provide a current briefing on the major outbreaks unfolding now, including Ebola in the Democratic Republic of the Congo and Uganda, New World screwworm in the United States, and the rapidly growing U.S. cyclosporiasis outbreak. Along the way, we answer the questions listeners are asking most.

We also examine several emerging signals, including H5 avian influenza in mammals, the potential for Vibrio vulnificus infections this summer, and why surveillance systems are just as important as laboratories when it comes to detecting outbreaks before they become national emergencies.

As always, you'll find annotated references, official dashboards, and links to additional resources in the companion blog post at InfectiousDose.com.

If you want the free, weekly companion newsletter to the episodes, Field Notes, subscribe here.

For most of human history, epidemics were something people endured—not prevented. Smallpox alone killed hundreds of millions of people, leaving survivors scarred, blinded, or forever changed. But hidden within that devastation was a remarkable observation: those who survived rarely became sick again.

In this episode, we explore the centuries-long journey from variolation to vaccination, following the observations of physicians, the experiences of milkmaids, the bold experiment of Edward Jenner, and the scientific breakthroughs that transformed an idea into one of medicine's greatest achievements. We'll also trace how Jenner's work inspired generations of scientists, eventually leading to vaccines against countless other diseases and the global eradication of smallpox.

This episode is part of our July series, Turning Points in Infectious Disease, exploring the discoveries that fundamentally changed humanity's relationship with disease. This week, we examine the moment prevention became possible.

For the full list of annotated citations, historical images, and additional resources, visit the companion blog post at InfectiousDose.com. And while you're there, subscribe to Field Notes, our free weekly newsletter featuring an expanded conversation about the episode, outbreak updates, infectious disease signals I'm keeping an eye on, and behind-the-scenes notes from Infectious Dose.