Biosecurity at the Border

THREE hundred and seventy-eight days after my departure on trip around the world, I entered immigration carrying a backpack with some food: a jar of Buglarian pepper spread, a jar of store-bought Italian truffle butter, and a mix of store-bought chocolates and candy from across Asia and Europe. To my knowledge, everything conformed to U.S. Customs and Border Patrol (CBP) regulations, but I had checked the relevant boxes declaring that I was carrying plant and animal products, just to be safe. When the immigration agent glanced at my customs form and asked what I was carrying, I answered and he dismissed me with, “You’re free to go.” When I asked him whether I needed to visit customs, his reply was “No.” Thirty minutes later, I was at customs with agents rummaging through my bags, courtesy of a chance encounter with a cheerful sniffer beagle and his CBP agent near the exit. One of the agents dropped the accusatory line “You should have checked yes to these things on your customs form.” “I did, both on paper and at the kiosk,” I told him, “I even told the immigrations agent what I had.” He was surprised. Everything I had ended up clearing customs, but what if I had been carrying something more dangerous or I had lied? A little dog was the country’s last line of defense, and he was successful only by chance.

To CBP’s credit, biosecurity is hard. I’m not an expert, but to me biosecurity is the defense of the country’s borders against threats to human health, agriculture, or environment, meaning the CPB’s job is to ensure that everyone and everything coming into the United States is “safe”. It requires constant vigilance, like that of a shepherd guarding his flock from wolves or a firewall protecting your computer from attacks. It’s one of those problems where you can succeed a thousand times, but one failure is all it takes to lose. And the price of loss can be huge, whether it’s economic damage or loss of human lives.

I wrote this essay to organize my thoughts on biosecurity at our country’s border, specifically what it looks like now and how it might look in the future. Biosecurity can be broken up into three steps: prevention, quarantine, and mitigation. Prevention deals in minimizing the number of threats that get to our border and includes informing people what can and can’t be shipped. Quarantine is the second step, and should prevention fail, a biosecurity threat should be caught at this stage—this is essentially biosecurity at our border. This is the customs check at airports and shipping hubs, and is the last chance to catch something before it enters the country. After that, the threat is in the country and we’ve got to tackle it with the last step: mitigation, or more simply, ‘dealing with it.’ This includes tracking the threat to understand it, trying to contain it within specific counties or states, and running costly cleanups of areas to try and eradicate it. This is the most expensive and worst step to get to, so efforts to control entry of threats during prevention and quarantine. Prevention often relies on good faith in those importing, because eradication of a pest worldwide is difficult. All this leaves is quarantine, the biosecurity at the border.

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WHAT biosecurity at the border looks like today depends on what threat you’re looking for and where you’re looking for it, but it broadly breaks down into searching for threats to agriculture and the environment, or threats to human health. In the first category are a panoply of pests ranging from microscopic bacteria to whole plants and animals, and they can be accidentally transported in everything from soil to fresh vegetables to wood carvings, making detection hard. The second category, threats to human health, is the transmission of anything that might cause disease in people. These threats are most often transmitted by people themselves or through human tissue, although the rising threat of bioterrorism has forced us to consider potential transport outside of the human body, like in glass tubes or sealed envelopes. While the threat of bioterrorism is what garners the most media attention (such as the 2001 anthrax attacks), accidental and intentional introduction of pests are far more costly, to the tune of $100 billion annually. So in thinking of biosecurity, it’s helpful to think beyond the potential for bioterrorism attacks to all forms of potential threats, both present and potential.

But while new biosecurity threats have emerged, the technology we have used to enforce biosecurity at the borders has changed little. The primary way to detect potential biosecurity threats is still sniffer dogs, animals trained to detect and alert CBP agents to the presence of a wide variety of smells. Though sometimes trained to directly smell a biosecurity threat, most dogs are instead trained to detect products that might harbor the potential threat, which then must be verified by hand and in lab. And while effective, these dogs are both expensive and time-consuming* to train and care for. The quality of your biosecurity is then limited by how many dogs you can have and how many hours they can work.

Beyond sniffer dogs, other technologies to detect biosecurity threats either don’t provide enough detailed information or are limited in what they can detect. For example, X-ray screening machines are now commonplace in customs agencies around the world, but their capabilities are limited to distinguishing between the presence and shape of inorganic matter (like computers) and organic matter (like books). In an attempt to detect biosecurity threats to human health, some countries have implemented mandatory body temperature checks of all passengers arriving in the country, but body temperature only rises after the initial stages of infection; a person who is infected can pass through only to become ill and transmit the illness to others afterward. And while detector machines have made their way to CBP to detect specific compounds or chemicals related to explosives, they can’t currently detect biosecurity threats.

Potential biosecurity threats are also becoming more complex and difficult to detect. As the technology sequence and synthesize DNA continues to fall in price and DIY biology increases in popularity, more potential biosecurity threats will arrive in the country in the form of nonliving DNA, the material that encodes the instructions for all living things on earth. DNA that poses a biosecurity hazard is nearly impossible to detect because it is present on nearly every surface of the Earth and is indistinguishable unless sequenced; under chemical analysis, the DNA for poliovirus would look nearly identical to DNA from humans or hamsters. As our technological progress continues, it becomes easier to simply encode weapons of biological warfare into an inert, white powder indistinguishable without complex analysis. But while it’s easy to respond to this potential threat by banning DNA transport or synthesis outright, doing so would wither our efforts to make new cures for diseases or develop helpful biological technologies. We need to balance our freedom to make and move DNA with its potential risks.

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GIVEN the changing landscape of biosecurity threats and our current reliance on older or limited technologies to detect them, what does the future of biosecurity at our borders look like? While I can’t claim to be a biosecurity expert, I can imagine that in the shape of tomorrow we’re going to need biological technologies that both detect specific threats and detect threats whenever anything out of the ordinary appears. We’re now looking to detect three kinds of threats: live things, such as animals, fungi, bacteria, or viruses; dangerous or toxic biological products and toxins, and inert DNA that may encode a potential threat. The best technologies will help us detect both specific threats we know of and help us flag strange things that might represent new potential threats.

There are several new technologies that might help us detect specific threats, including handheld machinery and paper-based diagnostics. When it comes to biosecurity, prevention remains the best option, and potential biosecurity threats are held at secure labs with restricted access, while DNA synthesis companies screen customer orders to determine whether it might encode a potential threat. But this doesn’t protect against individuals or small groups with expertise synthesizing genes/DNA abroad and attempting to bring them into the U.S. Nor does it detect signals that a person may be harboring a dangerous pathogen in their body, either intentionally and unintentionally. A test that rapidly checks DNA sequences for whether they are potential threats, as well as machinery to detect protein or compound-based signs of biosecurity threats would be helpful. In the long run, the shrinking cost and footprint of sequencing means that we may one day have a handheld machine that searches for a panel of sequences that may pose a threat is ideal. In the interim, paper-based diagnostics that detect specific DNA sequences, such as those that can identify different strains of Ebola or detect Zika, appear promising. We could create paper-based diagnostics that bind and signal presence of specific DNA sequences, as well as potentially toxic compounds or proteins.

But perhaps the most exciting advances are in the chance to detect threats without knowing they yet exist. We are increasingly able to sequence microbiomes from a variety of sources, and with some modifications we could extend these technologies to sequence the microbiomes of everything from imported mangoes to dried wood, establishing patterns of ‘baseline’ microbiomes that are present in all safe samples. We could then take samples the microbial populations on all imports coming into the U.S. to screen and match to these baseline microbiome populations, flagging those which show results out of the ordinary for follow-up and barring those that show signs of potential biosecurity threats. This gives us the first chance to detect or identify anything that is “unusual” instead of looking for known abnormal things. While the same thing could be done with people, some serious ethical questions would arise as to who has access to the data, what it reveals about an individual, and what we’re comfortable with as a society. Given these questions, predictive microbiome sequencing is best left as a tool goods imported or carried by people, rather than the people themselves.

When nutria were introduced for fur trapping or Asian carp introduced for aquaculture, nobody guessed that these animals cause millions of dollars in economic and environmental damage. Nobody predicted the SARS outbreak of 2002 or the 2014 Ebola epidemic. We still have difficulty with guessing what new threats lurk beyond our horizon of knowledge, but we’re getting better at predicting which threats on the horizon will be most damaging. By pursuing technology to detect both conventional pests and DNA-based potential threats, to both check for known potential threats and flag unusual changes from the norm, the biosecurity at the border will protect us better.

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*Note: this link estimates the cost of training a dog to detect explosives, not biosecurity hazards per se. I couldn’t find data on the latter, but training a dog to detect biosecurity hazards should be more expensive, because of the wide variety of things they must be trained to detect.