Infectious Dose

A hantavirus outbreak linked to a cruise ship has triggered fear, speculation, and growing debate online about whether the virus could be spreading person-to-person.

But what do we actually know right now?

In this episode, Heather breaks down the current hantavirus cruise cluster through the lens of science communication and uncertainty. Rather than focusing only on the facts of the outbreak, this episode explores a bigger question...

Imagine getting sick in the 1700s—before microbes were discovered, before antibiotics, and before infection had a clear cause.

In this Outbreak After Dark episode, we explore the strange, unsettling, and sometimes surprisingly insightful treatments used to fight disease in the pre-germ theory era. From bloodletting and mercury to tobacco smoke enemas and ...

There’s a virus you probably already have.

Epstein–Barr virus infects nearly 95% of adults worldwide. For many, it shows up once—fatigue, a sore throat, maybe a diagnosis of mononucleosis—and then disappears.

But EBV doesn’t disappear.

It stays, establishing lifelong infecti...

Murine typhus is a flea-borne bacterial infection that continues to circulate in parts of the United States, particularly in urban and suburban environments. But it’s often missed—because its symptoms are nonspecific, its rash may be subtle or absent, and it doesn’t fit the diagnostic patterns clinicians expect.

In this episode, we explore:

One year in, Heather steps back to reflect on what this podcast has become—and what changed along the way.

What started as a focus on clear, accurate science grew into something more layered: an exploration of how trust, systems, and lived experience shape the way people understand infectious disease. It also opened the door to creative storytelling, immersive formats, and conversations that challenged her own assumptions.

This epi...

You’re about to step inside a BSL-4 lab.

Not a tour. Not an explanation.

An experience.

You’ll move through clearance. Suit up. Connect to air. And cross the threshold into one of the most controlled environments in the world.

Inside, the work is methodical. Quiet. Precise.

And everything you think you know about these labs… starts to shift.

Put your headphones on. And step inside.

More information and resources can be found at inf...

The plague doctor: a symbol of fear, medicine, and mystery. But were they really the heroes we imagine—or something more complicated?

In this Outbreak After Dark episode, we explore the real history behind the iconic beaked mask. From medieval theories of “bad air” to the rise of quarantine systems and early public health policy, we follow the evolution of ...

What if the biggest misunderstandings about vaccine safety aren’t just about the science—but about how the system communicates it?

In this updated guided tour of the Vaccine Safety Series, Heather maps the episodes that break down how vaccines are tested, monitored, and evaluated—and where communication and institutional failures have contributed to confusion and mistrust.

This episode is designed to help you navigate the series—wh...

When we talk about misinformation in public health, we usually imagine social media, conspiracy theories, or individuals misunderstanding science. But what if some of the most influential misinformation starts somewhere else?

In this episode of Infectious Dose, Heather speaks with biomedical researcher Dr. Mark Ungrin about how scientific ideas move thr...

Mpox isn’t just a headline from 2022.

In this episode, we explore what scientists have learned about mpox since the global outbreak — from how the virus moves through the body to why its lesions can be so painful. We break down the biology of orthopoxviruses, the surprising role of human immune enzymes in shaping viral evolution, and the emergence of ...

What if attraction isn’t entirely yours? In this Outbreak After Dark episode, Heather, Kate, and Sam gather around the campfire to explore the parasites, fungi, and viruses that manipulate behavior in the name of survival. We’re talking:

• Toxoplasma gondii, the parasite that dampens rodents’ fear of cats
• The lancet liver fluke, which turns ants into grazing bait
• Ophiocordyceps, the real-life “zombie ant” fungus
• Baculoviruses th...

Nipah virus scares virologists, and for good reason. It infects endothelial cells and neurons. It can cause fatal encephalitis. It spreads from bats to humans, and sometimes between people. So why does it keep burning out? In this episode of Infectious Dose, we examine:

• Henipavirus biology and receptor usage (eph...

Syphilis is back—and it never really left. In this episode, we break down how a curable, preventable infection is resurging to cause a public health crisis across the U.S., and globally, especially among pregnant people and newborns. We unpack the science behind Treponema pallidum, the public health failures driving the crisis, and why trust in health systems is still broken—from Tuskegee to ...

This short, standalone episode is a statement of ethics.

It explains why this podcast will not remain silent in the face of state violence, the dismantling of public health, and the normalization of harm against vulnerable people. It clarifies the ethical boundaries that guide the work behind Infectious Dose: that science is for everyone, but cruelty, authoritarianism, and the protection of abuse are not neutral positions.

This epi...

RSV is one of the most common respiratory viruses — and a leading cause of hospitalization in young children worldwide.

In this solo episode, I explain what RSV is, how it spreads, and what illness typically looks like in babies, children, and adults. We cover when RSV can be managed at home, how to recognize breathing-related red flags, when to go to...

Spiders inspire some of our deepest fears—but are they actually as dangerous as we think? In this Outbreak After Dark episode, Heather, Sam, and Kate dig into the real science behind spiders, venom, and so-called “spider bites,” separating evidence from exaggeration. Along the way, they unpack persistent myths, medical misattribution, and why spiders loom so large in outbreak lore—despite rarel...

What are biological weapons—and what are they not?

In this episode, Heather is joined by bio-risk consultant and biodefense researcher Conor Browne for a grounded, reality-based conversation about biological weapons, biodefense, and why public discourse around these topics so often goes wrong.

Together, they unpack what actually defines a biological weapon, why intent and delivery matter, and how real historical programs differ fro...

In this episode of Infectious Dose, Heather McSharry talks with Terry Virts—retired NASA astronaut, Air Force colonel, and candidate for Congress in Texas—about what happens when leadership ignores science.

Drawing on his experience in aviation, spaceflight, and risk analysis, Terry discusses the real-world consequences of sidelining evidence in public ...

This week in “Seasonal, Not Safe,” we confront the truth about influenza in 2025–2026. It’s not “just the flu.” From the tragic stories of children lost to fast-moving infections, to the science of how influenza spreads, mutates, and turns deadly — this episode explores what’s really happening this season. We break down the rise of Subclade K, current global flu patterns, new U.S. vaccine policy controversies, and what makes the fl...