The Fungus, the Students, and the Protecting Our Border from Pathogens

A Fungus and a Federal Case

In June 2025, the United States Department of Justice announced an unusual case. It is accusing two Chinese citizens of trying to smuggle a fungus into the U.S.. The fungus, Fusarium graminearum, is a pathogen I never worried about until I heard about this case. Fusarium does not directly threaten human health. Rather, it threatens important food crops, including wheat, barley, maize, and rice. In the worst-case scenario, it can destroy harvests and potentially contaminate foods with toxins that can make people sick, such as the appropriately named “vomitoxin.”

I became intrigued with this story, because it sits at the intersection of bioterrorism, food safety, and border control, the latter of which is one of the hottest political issues in the U.S. right now. 

Why the U.S. Monitors Every Fruit, Leaf, and Soil Sample at the Border

If you have traveled internationally, you’ve probably noticed something about the document (now primarily electronic) that you need to complete when you enter the U.S.. and the questions you may get from a uniformed guard when you try to exit the airport: are you carrying any fruits, vegetables, plants, or soil from your international travel?

I remember my teenage son getting stopped by the customs officers when they found he had an apple in his backpack after we were traveling back into the U.S., while stationed in Addis Ababa, Ethiopia. They interrogated him where the apple came from and wondered why we did not realize how dangerous this was. I did, of course, but did not even realize he had an apple in his backpack. 

While it felt like an overreaction, there is a reason these rules are in place. The United States is one of the world’s largest producers and exporters of food. Our agricultural economy is vast and complex, but also profoundly vulnerable. It rests on monocultures, industrial-scale supply chains, and a narrow base of pest and pathogen resistance. Even one infected apple could cause an outbreak in our crops, causing billions of dollars in lost harvests and upending the lives of people who depend on growing fruits and vegetables. The citrus greening disease that crippled Florida’s orange industry, for example, was introduced accidentally, likely through infected Asian citrus psyllids. 

Now consider Fusarium graminearum, the fungus that these two people are accused of bringing into the U.S. While this fungus already exists in parts of the U.S., different strains possess different levels of virulence, toxin production, and climate adaptation. Introducing a new variant into an area where it isn’t currently circulating or into a crop population that hasn’t developed resistance could cause an outbreak. These pathogens are almost impossible to eradicate, fungal spores can persist in the soil for years, and they can travel via the bottom of our boots, on birds, or in the breeze to other fields.

That is why U.S. Customs and Border Protection, working in tandem with USDA’s Animal and Plant Health Inspection Service (APHIS), enforces strict rules around agricultural imports. In addition to fruit and soil, other samples, such as for museums or research, must go through biosafety protocols, permitting systems, and controlled shipping procedures.

So, yes, these rules can be annoying to follow, because they slow down research, delay deliveries, and occasionally ensnare teenager boys with apples. But they exist because the food we grow is a vital part of our economy, nutrition, and security. 

Agroterrorism Is Real Risk

Agroterrorism refers to the deliberate introduction of plant or animal pathogens with the intent to cause economic disruption, food insecurity, or social chaos. In a country where agriculture accounts for over $1 trillion in GDP and one in ten jobs, the impact of a well-targeted biological attack on crops or livestock would be immense and immediate.

In 2002, the Department of Homeland Security declassified evidence of terrorist interest in targeting U.S. agriculture, particularly with pathogens such as foot-and-mouth disease (FMD). FMD is a virus that spreads rapidly among livestock, harming cattle, pigs, sheep, and goats. The U.S. has not had an outbreak of FMD since 1929, but an intentional release—say, in a Midwest feedlot or major cattle processing plant—could shut down the meat and dairy industries overnight. The mere suspicion of contamination would be enough to halt exports, trigger mass culling, and cause cascading economic damage. What makes these threats especially difficult is their invisibility, often spreading far and wide before we detect them.

The Blurred Line Between Biosecurity and Geopolitics

On paper, the case involving the Chinese students and the Fusarium spores looks like a straightforward breach of U.S. import law. The two were graduate students, romantically involved and both affiliated with agricultural research. One student allegedly carried a bag containing fungal samples and attempted to enter the country without appropriate permits or containment procedures. Whether this was for legitimate research, careless ignorance, or something more intentional will be up to the courts to decide.

This is case is particularly interesting, because, over the past decade, scrutiny of international students and researchers, especially those from China, has intensified dramatically. The Trump administration instituted visa restrictions for students in certain STEM fields. Government agencies launched investigations into university labs with Chinese funding or collaboration. The NIH recently paused grants to academic centers overseas. The message, sometimes stated outright, has increasingly been that science from abroad poses a threat to U.S. national security.

And while some concerns are legitimate, such as espionage, intellectual property theft, unauthorized tech transfer, I worry that the net has been cast indiscriminately. Graduate students, postdocs, and visiting scholars have found themselves detained, interrogated, and deported, often with little explanation and no recourse. The idea that academic collaboration is a conduit for subversion has taken hold in parts of the American political psyche.

That context matters here. Because it complicates our reading of events. Is this a case of a researcher bypassing regulations for convenience? Or one of malice? Or one of disproportionate suspicion rooted in nationality?

When I Carried Pathogens Through the Airport

My own experience with transporting biological samples into the United States is far less dramatic than what’s described in the DOJ indictment. But it’s a useful reminder that the line between caution and criminalization can be thin, and often determined not by the substance of your actions, but by how they’re perceived.

Back in 2002, while working as an Epidemic Intelligence Service (EIS) officer with the CDC, I was dispatched to investigate an outbreak of norovirus on a cruise ship that had docked in Curaçao. (Read more about the investigation here) Vomiting and diarrhea were widespread. I collected stool specimens, surface swabs, and environmental samples to bring back to Atlanta for testing. These weren’t high-risk specimens. It was the same type of poop that gets flushed into airplane toilets every day. But I was still questioned at the Miami airport. Why did I have these? How were they packaged? Who gave me permission?

I had done everything by the book: biosafety procedures, cold chain logistics, and CDC authorization paperwork. But that didn’t make the process smooth. I wasn’t just carrying plastic tubes. I was carrying evidence of an outbreak, of a public health response, of the invisible infrastructure that keeps disease from spreading. But I can’t help wondering what would have happened if I had been a foreign national, or if I hadn’t spoken perfect English, or if my documentation hadn’t matched exactly what the airport personnel expected to see. 

The Future of Food, Security, and Scientific Trust

There are two equally important truths in this story. One is that Fusarium graminearum is a real threat. It can cause real damage to American crops, and anyone transporting it across borders should be subject to the highest standards of biosafety and legal compliance. The second is that international scientific collaboration is not a threat; it is the only way we will solve many of the challenges facing humanity, from emerging pathogens to climate-driven crop failures.

What concerns me most is that we are increasingly treating those two truths as incompatible, that the people who bring knowledge, skills, and research capacity from overseas are automatically presumed to be suspect. That the desire to keep our country safe is overriding the more difficult task of making our country better through exchange, collaboration, and curiosity.