Podcast

Infectious Dose

Life Sciences, Science

Infectious dose is the shot of science you need to protect yourself from misinformation. Heather McSharry, PhD, an expert in viral pathogenesis, brings her blog to the airwaves to help bridge the dangerous gap between the science of infectious diseases and public misperception. On the podcast website, infectiousdose.com, all episodes have corresponding blog posts with the information contained in the episode along with links or PDFs for all sources used. To prevent unwelcome surprises, episodes with limited, mild profanity are marked as explicit.

*Podcast intro and outro music are adapted from Heather Nova’s song, I Miss My Sky. Used with permission.

Episodes
97
Releases
Weekly
Typical length
24 min
On air since
2025
Latest episode
4 days ago

Episodes

97 episodes, newest first

  1. S2E45 The Devil of Hawthorn Mill

    Season 2, Episode 45

    Show notes

    We interrupt this program to bring you a brief bulletin...

    In the quiet town of Hawthorn Mill, a missing teenage girl has been found wandering barefoot along a country road. She remembers nothing. Authorities insist there's no reason for alarm.

    But the bulletins keep coming.

    For the final installment of Infectious Dose's Month of the Macabre, we're turning back the dial to 1938 with a special full-cast audio drama inspired by Orson Welles and the Mercury Theatre's legendary broadcast of The War of the Worlds.

    Through vintage radio programming, breaking news reports, and increasingly urgent transmissions, The Devil of Hawthorn Mill unfolds in real time as a small community confronts something it cannot explain.

    Put on your headphones, tune your radio, and stay with us. The broadcast is just beginning.

    A special Halloween production featuring our volunteer ensemble cast.

    This is a fictional audio drama. The events, community, and central illness are invented, although elements of the underlying science are real.

    Full episode transcript and cast acknowledgments available in the companion blog post on the Infectious Dose website.

    1 hr 5 min
  2. S2E44 A Year Around the Fire: Our First Anniversary

    Season 2, Episode 44

    Show notes

    One year. Three original hosts. Zero reliable scoring systems.

    It's the first anniversary of Outbreak After Dark, and the original campfire crew is back together!

    Heather welcomes Kate and Sam around the fire for a look back at the strange, hilarious, and occasionally horrifying moments that shaped Year One.

    Along the way, we explore how the show evolved from three friends talking about infectious disease into immersive storytelling, unexpected guests, and an increasingly elaborate collection of recipes with questionable names.

    And because we can't just have a normal anniversary celebration, Kate and Sam compete in an infectious-disease mini-game featuring forgotten quotes, survival decisions, and a mystery pathogen. The rules are clear. The judging is another matter.

    On the anniversary menu: The Menu of Misfortune—four recipes randomly selected from our first year, including House Call, Symbiosis Spritz, Rumor Mill, and Pecan Pustules.

    We're also looking ahead to Year Two, with new guests, Outbreak After Dark Gathering Kits, The Night Library, and the possibility of a full-fledged infectious-disease game show.

    Find the episode overview, downloadable transcript, and all four anniversary recipe cards in the companion blog poston the Infectious Dose website.

    Keep the embers warm. This is Outbreak After Dark.

    38 min
  3. S2E43 The House of Căpușan

    Season 2, Episode 43

    Show notes

    An isolated village. A mysterious outbreak. A physician whose patients trust him with their lives.

    When American scientist Dr. Helen Seward travels to Romania's Carpathian Mountains to investigate cases of Crimean-Congo hemorrhagic fever, she expects to find infected ticks, complicated exposure histories, and a community struggling to contain a dangerous disease.

    What she finds is something far stranger.

    The ticks are appearing where they shouldn't. Medical records don't quite add up. And the village's beloved physician, Dr. Căpușan, seems to know more about the outbreak—and its unusual vectors—than he's willing to reveal.

    Inspired by Bram Stoker's Dracula, The House of Căpușan is an original Infectious Dose audio drama that brings infectious-disease science into the shadows of Gothic horror.

    💀 Month of the Macabre 2026

    🎬 This week's #SickFlicks: Bram Stoker's Dracula (1992) and Nosferatu (2024). Two atmospheric explorations of vampirism, contagion, and the dangerous intimacy of blood.

    🎧 Headphones recommended. This is an immersive, audio-only story.

    🩸 Next week: It's the final week of Month of the Macabre, and we're celebrating with two special releases! Original Outbreak After Dark cohosts Kate and Sam return for an anniversary reunion with the original trio back together.

    Then, on Friday, October 30—the 88th anniversary of the 1938 War of the Worlds radio broadcast—we're bringing you The Devil of Hawthorn Mill, an original audio drama inspired by Orson Welles' legendary broadcast.

    📻 Tune in to WIDX. The broadcast is about to be interrupted.

    Visit theepisode blog postfor the overview and downloadable transcript.

    35 min
  4. S2E42 Just a Little Wider: Please Remain Still

    Season 2, Episode 42

    Show notes

    Just a Little Wider | Month of the Macabre

    He's already been waiting more than an hour. He's sick, exhausted, and ready to leave. But the dentist can see him now. Surely it won't take long.

    Then the dentist finds something unusual.

    As the exam continues, the patient grows increasingly ill. The dentist's behavior becomes more disturbing. Familiar sounds begin to suggest terrible things, and with every passing minute, it becomes harder to tell whether the danger is coming from the person holding the instruments, or from something happening inside the patient's own body.

    Inspired by the real possibility that systemic infections can leave clues in the mouth, Just a Little Wider is an immersive work of medical horror in which illness, perception, and reality become impossible to separate.

    💀 Month of the Macabre 2026 — An original Infectious Dose horror story.

    🎬 This week's #SickFlicks: Dead Ringers (1988) and The Autopsy of Jane Doe (2016)—two unsettling films about medical authority, the vulnerability of the human body, and exams that take a horrifying turn.

    🎧 Headphones recommended.

    Find the complete episode transcript and more at Infectious Dose.

    10 min
  5. Outbreak Watch: October 9, 2026 Bonus

    Show notes

    In this week's Outbreak Watch, we're examining the latest developments in the DRC Ebola outbreak, Pennsylvania's ongoing measles outbreak and a new development in the US H5N1 outbreak. Finally, we separate evidence from speculation surrounding reports of a possible laboratory-associated infection in Russia.

    Outbreak Watch is part of Infectious Dose, bringing you outbreak developments, epidemiological context, and the science behind the headlines.

    Find the full transcript, annotated sources, and additional resources at Infectious Dose.

    9 min
  6. S2E41 The Collection: Exhibits to Die For

    Season 2, Episode 41

    Show notes

    The museum is closed. The exhibits aren't finished changing.

    In the first episode of Month of the Macabre 2026, a routine after-hours visit to a museum of infectious disease history takes an unexpected turn. Past the familiar scenes of Broad Street, the 1918 influenza pandemic, and SARS in Toronto, a new gallery has appeared: a modern train station displaying an outbreak that hasn't happened yet.
    Then the exhibit changes.

    And changes again

    The Collection is an immersive Infectious Dose audio story about infectious disease history, transmission, outbreak investigation, and what happens when knowing the future doesn't necessarily mean you can control it.

    🎬 This week's #SickFlicks to accompany the episode: Annihilation (2018) and The Endless (2017)—two stories in which reality begins behaving according to unfamiliar rules, leaving the people inside to figure out what those rules mean.

    Check out the companion blog post for citations and transcript.
    🎧 Headphones recommended.

    36 min
  7. S2E40 Monsters, Movies, and Microbes: When Infection Becomes Horror

    Season 2, Episode 40

    Show notes

    It’s horror movie night, but Heather can’t stop seeing infectious disease in the monsters.

    Heather is joined by her friend Valerie to explore the real biology behind some of horror’s most enduring fears: tuberculosis and vampire lore, rabies and werewolves, zombies as outbreak epidemiology, neurological disease and possession, and the strange biology behind The Last of Us, The Thing, and Alien.

    Plus, Valerie plays the hilarious Horror Movie or Medical Literature? and discovers that when it comes to horror, evolution has had a considerable head start.

    So grab a drink, pick a movie, and remember the most important public-health lesson horror has apparently failed to teach us: stop hiding bites.

    Annotated citations and episode recipes available in the companion blog post.

    48 min
  8. S2E39 Skeeters on a Plane: The Curious Tale of Airport Malaria

    Season 2, Episode 39

    Show notes

    How do eight people get falciparum malaria in Germany when none of them traveled somewhere malaria is circulating? The answer may be that they didn't have to travel. The mosquito did.

    This episode follows the investigation into a cluster of malaria cases linked geographically or occupationally to Frankfurt Airport, including three deaths. We'll look at how an infected mosquito can carry malaria across continents, why airport malaria can be difficult to diagnose, what previous cases tell us about this rare phenomenon, and what investigators still don't know about the current outbreak.

    Find annotated citations and transcript in the companion blog poston the Infectious Dose website.

    19 min
  9. Outbreak Watch: September 18, 2026 Bonus

    Show notes

    This week on Outbreak Watch, we’re tracking signs that Ebola transmission may be stopping in some parts of the DRC while continuing elsewhere; what still hasn’t happened with New World screwworm in the U.S.; Florida’s growing locally acquired dengue outbreak; an unusual increase in rabies exposures and preventive treatment; Pennsylvania’s four measles-associated deaths and request for CDC assistance; anthrax moving from wildlife into humans in Zambia; and a strange cluster of falciparum malaria cases near Frankfurt Airport.

    Plus: what should we actually watch for next to know when each of these situations has changed?

    Full citations, transcript, and other resources can be found in the companion blog post at the Infectious Dose website.

    17 min
  10. S2E38 Dengue Next Door: How an Imported Virus Becomes a Local Outbreak

    Season 2, Episode 38

    Show notes

    In this episode of Infectious Dose, we follow the dengue transmission chain from traveler to mosquito to locally acquired infection. How does dengue become infectious inside a mosquito? Why do most imported infections go nowhere while some seed outbreaks? What can mosquito traps and viral genomes tell investigators? Why can a jump in reported cases give a misleading picture of when infections actually occurred? And at what point would local transmission become something more persistent?

    Using Florida's current dengue outbreak as a case study, we'll explore the space between introduction, local transmission and establishment and why a growing outbreak does not automatically mean dengue has become endemic.

    Full annotated citations and additional resources are available in the companion blog post at http://InfectiousDose.com. You can also sign up there for Field Notes, the Infectious Dose newsletter, for outbreak updates, new episodes and other infectious-disease stories.

    20 min
  11. S2E37 Every Clade, Everywhere, All at Once: The Strange Emergence of Candida auris

    Season 2, Episode 37

    Show notes

    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 http://InfectiousDose.com.

    24 min
  12. S2E36 Because Mom Said So: The Infection Myths We Grew Up With

    Season 2, Episode 36

    Show notes

    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.

    32 min
  13. Outbreak Watch: August 28, 2026 Bonus

    Season 2

    Show notes

    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 postat Infectious Dose.

    Subscribe to Field Notes to continue the conversation around episodes and weekly outbreak updates.

    21 min
  14. S2E35 Campfire Curiosities: The Can, the Crabs, and the Note

    Season 2, Episode 35

    Show notes

    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.

    27 min
  15. S2E34 Night Hike: Following Microbes Into the Dark

    Season 2, Episode 34

    Show notes

    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.

    23 min
  16. S2E33 Afternoon Picnic: How Microbes Move Through a Summer Meal

    Season 2, Episode 33

    Show notes

    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.

    Subscribe to Field Notesto continue the conversation.

    35 min
  17. Booster Dose - The Vaccine Executive Order: What You Need to Know Bonus

    Season 2

    Show notes

    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

    27 min
  18. Outbreak Watch: August 7, 2026

    Season 2

    Show notes

    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.

    Subscribe to the free Field Notes newsletter to continue the conversation around the weekly episodes.

    19 min
  19. S2E32 Morning Swim: The Hidden Microbial World of Freshwater Lakes

    Season 2, Episode 32

    Show notes

    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.

    Subscribe to the free weekly newsletter, Field Notes, to continue the conversation around each episode.

    23 min
  20. S2E31 For Medicinal Purposes: Whiskey, Jazz, and Germs

    Season 2, Episode 31

    Show notes

    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.

    Subscribe to the Field Notes newsletter to continue the conversation and get updates on outbreaks and a peek behind the scenes.

    24 min

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