GEOFF BENNETT: What would happen if the next major national security threat wasn't a missile or a bomb, but a deliberately engineered pathogen?

That's the premise of the new book by Pulitzer Prize-winning investigative journalist Annie Jacobsen.

The book is called "Biological War: A Scenario."

I spoke with her for the PBS News podcast "Settle In," and we discussed America's preparedness for biological threats, what recent disease outbreaks reveal about vulnerabilities in our public health system, and why she believes that knowledge, not panic, is one of our best defenses.

Here's part of that conversation.

Well, let's start with the germ at the center of this book.

It's a form of plague, and it's engineered by Soviet scientists during the Cold War.

And the design is such that if you take the antibiotic that should save your life, that is what actually kills you.

Explain how that -- how that works.

ANNIE JACOBSEN, Author, "Biological War: A Scenario": Well, thank you for pointing out that it's tied to the Soviet bioweapons engineers of the Cold War, because my book is sold in the nonfiction department.

I write about science fact, even though it reads like science fiction.

And so I want readers to always feel like they are embedded in truth.

And there it was this horrific bioweapon created by the Soviets during the Cold War.

And this is 40 years ago, before genetic engineering, that -- what they called a super plague weapon.

And, of course, many people know about plague bubonic plague.

This is a form that goes in the lungs called pneumonic plague.

And as you mentioned, it is what is called a chimera pathogen, chimera, that Greek mythological idea of a beast of multiple parts, the head of a lion, the body of a serpent, two organisms at once.

The chimera is a genetically modified pathogen, so that it has a booby trap effect.

So what you think is going to cure you will kill you in an even more horrific way.

GEOFF BENNETT: Fast-forward to the current moment.

There is this question, if our government can't track a parasite in the lettuce supply with a two-month head start, what happens when the pathogen is engineered and someone is deliberately hiding the source of it?

ANNIE JACOBSEN: I mean, that is a rhetorically good question.

And I think that when I see the kind of lettuce outbreak or even the hantavirus outbreak in May overseas, when you look at Ebola in West Africa right now, I think that the information, good information coming out of those outbreaks and or epidemics, you can start to realize something must be done, the system isn't working the way it should, and people can really kind of demand change, because there is so much money involved.

You know, the U.S.

Department of Health and Human Services, HHS, is in charge of a biological incident or outbreak.

CDC is below HHS.

Most of your viewers, most of the people in the world don't know what HHS is, and yet it has a budget twice that of the Defense Department, twice.

So that's a lot of money.

Yes, it involves Medicare and Medicaid.

But there's still a problem with that we don't know -- we, the royal we, don't know the source of the lettuce outbreak.

GEOFF BENNETT: You have spent years interviewing former defense secretaries, senior administration officials, experts.

When you were -- as you said, when you were writing the book about the nuclear threat, they would describe the biological threat as shark in the water.

What were they most afraid of?

ANNIE JACOBSEN: Well, you certainly get that sense in the book, I think, because I give it to you in no uncertain detail.

But the big general idea is echoed in a Defense Department document I found.

It's called a threat spectrum.

And this is an unclassified document, but it looks at weapons of mass destruction on a scale.

And, of course, nuclear weapons are at the far end of the scale as the most destructive.

No one would argue with that.

But biological weapons are a very close second.

And even more disconcerting, they are -- quote - - "the greatest overall threat."

And that is because the barrier for entry is so incredibly low.

You need fissile material to make a nuclear weapon.

You need a delivery system like an ICBM.

We know now, particularly with A.I.-enabled bio, the barrier for entry is so low, high-ranking officials tell me a kid in a basement with very -- a bad actor with a nefarious mind in a basement with very little knowledge of biology can make a biological weapon.

GEOFF BENNETT: There is this idea too that, were this to happen, God forbid, no one's coming to save us.

So what can we do to be prepared, apart from stockpiling penicillin and rubbing alcohol and peroxide in our Cabinets?

Like, what can the average person do to prepare for something like this?

ANNIE JACOBSEN: You have hit upon like an interesting catch-22, where no one's coming from us, and what do we do and do we panic?

In all the Defense Department war gaming I came across, fear of infection, that actual quote, is repeated continually.

"Fear of infection will lead to."

And what it always leads to is anarchy and insurrection.

And all of the Pentagon war games know that or assume that.

And so that is where their plans in place we can talk -- if we have time to talk about that are shocking.

But on the fear of infection point, I would say, as far as the public is concerned -- and this is like me speaking not just as a journalist, but as a mom, that the way to prevent fear and panic is knowledge.

And so having a little bit of knowledge goes a very long way.

GEOFF BENNETT: You can watch that full episode of "Settle In" -- it's a good one -- and more on our YouTube page or wherever you get your podcasts.