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 infection inside B cells—the very cells responsible for immune memory. Most of the time, the immune system keeps it under control. But EBV is not passive. It shifts between latency and reactivation, adapts to immune pressure, and in some cases contributes to cancer and chronic disease.

In this episode, we explore:

• How EBV infects epithelial cells and B cells
• The molecular mechanisms that allow it to persist for life
• Latency, reactivation, and immune system control
• Why EBV is linked to cancers like Hodgkin lymphoma and nasopharyngeal carcinoma
• How host genetics and viral variation shape disease risk
• And what new research suggests about finally preventing infection

This isn’t just a story about a virus. It’s a story about what happens when infection never truly ends.

Want to go deeper? Field Notes is my free, weekly newsletter where I expand on one key idea from each episode. It’s not a summary—it’s a shift in perspective. Subscribe here.

Annotated citations are in the companion blog post at infectiousdose.com

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:

• How murine typhus is transmitted (and why fleas matter more than you think)
• The role of urban ecology, including opossums, rodents, and flea vectors
• What happens biologically when Rickettsia typhi infects endothelial cells
• Why these infections are frequently misdiagnosed or overlooked

This is not just an episode about typhus—it’s about how recognition fails, and what that means for the diseases hiding in plain sight.

Also in this episode, introducing Field Notes, the new, free email newsletter companion to the episodes - not a recap, but what stays with Heather after the episodes. Issues are sent mid-morning after episodes drop.

Sign up on the website if you want to receive Field Notes.

Companion blog post with transcript and all citations is at infectiousdose.com

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 episode includes a few short clips from the past year—moments that capture the range of the show, from unsettling to unexpected to quietly funny.

If you want to keep following those threads a little further, Heather is starting a free, weekly companion called Field Notes—a place to sit with one idea from each episode and see where it leads. The first issue arrives with next week's episode.

Whether you’ve been listening from the beginning or just found your way here, thank you so much for listening. We're glad you’re here.

Companion blog post at Infectiousdose.com