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PODCAST

Infectious Dose

Infectious Dose

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

science life sciences

All Episodes

47:40

S2E40 Monsters, Movies, and Microbes: When Infection...

Infectious Dose ·

2026/09/30

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

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19:10

S2E39 Skeeters on a Plane: The Curious Tale of...

Infectious Dose ·

2026/09/23

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

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17:12

Outbreak Watch: September 18, 2026

Infectious Dose ·

2026/09/18

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

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20:01

S2E38 Dengue Next Door: How an Imported Virus Becomes...

Infectious Dose ·

2026/09/16

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

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24:18

S2E37 Every Clade, Everywhere, All at Once: The...

Infectious Dose ·

2026/09/09

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

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32:26

S2E36 Because Mom Said So: The Infection Myths We...

Infectious Dose ·

2026/09/02

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

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21:24

Outbreak Watch: August 28, 2026

Infectious Dose ·

2026/08/28

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

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27:06

S2E35 Campfire Curiosities: The Can, the Crabs, and...

Infectious Dose ·

2026/08/26

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

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23:09

S2E34 Night Hike: Following Microbes Into the Dark

Infectious Dose ·

2026/08/19

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

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34:50

S2E33 Afternoon Picnic: How Microbes Move Through a...

Infectious Dose ·

2026/08/12

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

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26:35

The Vaccine Executive Order: What You Need to Know

Infectious Dose ·

2026/08/11

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

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18:53

Outbreak Watch: August 7, 2026

Infectious Dose ·

2026/08/07

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

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23:14

S2E32 Morning Swim: The Hidden Microbial World of...

Infectious Dose ·

2026/08/05

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

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24:18

S2E31 For Medicinal Purposes: Whiskey, Jazz, and Germs

Infectious Dose ·

2026/07/29

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

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19:27

S2E30 Do No Harm: The Birth of Infection Prevention

Infectious Dose ·

2026/07/22

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

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14:38

Outbreak Watch: July 17, 2026

Infectious Dose ·

2026/07/17

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

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28:05

S2E29 A Shot in the Dark: The Science That Outsmarted...

Infectious Dose ·

2026/07/15

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

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24:56

S2E28 Holding the Line: How Prevention Became...

Infectious Dose ·

2026/07/08

For much of history, disease claimed more soldiers than combat. In this episode of Infectious Dose, we trace the evolution of military preventive medicine—from the Revolutionary War to the present day—and explore how armies came to view infectious disease as an operational threat rather than an unavoidable consequence of war. We'll follow the story through George Washington's smallpox inoculation campaign, Florence Nightingale's sanitation reforms during the Crimean War, Walter Reed and William

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23:16

S2E27 On the Fly: Lessons From a Screwworm

Infectious Dose ·

2026/07/01

In the mid‑20th century, ranchers across the southern United States watched livestock being literally eaten alive by a flesh‑eating parasite: New World screwworm. This episode tells the story of how an entomologist’s “absurd” idea helped eradicate screwworm from North America, and why that victory is suddenly back in the spotlight as new cases appear in Texas in 2026. We follow the parasite’s biology, the development of the Sterile Insect Technique, the massive binational infrastructure that kept

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30:23

S2E26 Dusk Hunters: The Anatomy of a Blood Meal

Infectious Dose ·

2026/06/24

June's Summer Rain series wraps up with a tribute to Gulf Coast mosquitoes. In this episode of Outbreak After Dark, Heather and Kate explore the anatomy of a mosquito bite—from the moment a female mosquito detects carbon dioxide to the itch that keeps you awake long after she's gone. Topics include: • How mosquitoes find humans • Why only female mosquitoes take blood meals • The surprising anatomy hidden inside a mosquito's proboscis • Why mosquito bites itch • Histamine, nerves, and the science of

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94 results

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