The screwworm outbreak shows that food security depends on invisible systems

The story began, as many national failures do, in a place too small to notice.

A calf in Texas had a wound. In that wound were larvae. The larvae belonged to the New World screwworm, a parasitic fly whose young feed on the living tissue of warm-blooded animals. The wound was local. The system behind it was continental.

For decades, Americans did not have to think about screwworm. That was an achievement. The parasite had been pushed out of the United States, Mexico, and much of Central America through one of the triumphs of modern agricultural science: the mass release of sterile male flies. Wild females mated with them and produced no offspring. A biological threat was suppressed by biology itself.

But science alone did not do it. Aircraft, laboratories, livestock inspections, border controls, veterinarians, rancher reporting, quarantine rules, and international agreements did it. The barrier that held screwworm back was made of competence.

Now the fly is back.

Prevention disappears when it works

The return of New World screwworm shows what happens when prevention systems disappear from public attention. A flesh-eating fly that had been held back for decades by sterile-insect production, veterinary surveillance, animal-movement controls, and international cooperation is now testing America’s food-supply defenses.

The lesson is bigger than one parasite. Outbreaks become economically and humanly expensive when countries neglect the quiet diplomatic and technical systems that stop biological risk before it becomes crisis.

That is the awkward virtue of prevention. When it works, it does not throw a parade. It produces no ruined herds, no emergency appropriations, no trade panic, no photographs fit to frighten the public, and no committee room full of men discovering, with grave faces, what they had declined to maintain.

Success becomes silence. Silence becomes habit. Habit becomes a budget cut.

Then the bill arrives.

In the screwworm case, it may arrive first at the ranch gate: animals checked wound by wound, movement permits delayed, markets slowed, agencies scrambling, taxpayers paying for emergency measures, and consumers meeting one more invisible failure at the meat counter. The animals pay most directly. They always do. A parasite that should have remained contained does not negotiate with the creature it enters.

Biosecurity is supply-chain infrastructure

Food supply chains are not just roads, ports, warehouses, and refrigerated trucks. They are living systems moving through a living world. Cattle move. Insects move. Wildlife moves. People move. Climate changes the map under everyone’s feet, and trade carries risk along with goods.

That is why biosecurity is supply-chain infrastructure.

A cattle market runs on more than animals and bids. It runs on the belief that someone competent has looked before the gate was opened. A border crossing is the same. Without real inspection, it is only a painted arm rising and falling over uncertainty.

Quarantine requires discipline before fear has taken command. A sterile-fly program, strange as it may sound to the comfortable citizen, depends on the old virtues governments are forever praising and too often neglecting: enough capacity, clear orders, reliable routes, trained technicians, and the patience to keep doing exact work after applause has gone elsewhere.

Here diplomacy ceases to be a speech and becomes a craft. It is the unglamorous labor of keeping agencies honest, neighbors capable, laboratories ready, and reports moving before rumor does. The rancher needs a fast channel for trouble. The country needs foreign partners who can act without vanity, delay, or theatrical suspicion.

When those habits fail, the border fails. Then the parasite exacts a terrible price.

No nation can manage this alone. Screwworm does not honor a flag. Avian flu does not stop for customs. Foot-and-mouth disease does not wait while diplomats improve the wording. African swine fever does not care whether the farm is small, modern, domestic, or export-oriented.

Outbreak prevention is a diplomatic skill because biology crosses political lines faster than governments do. The countries that understand that fact spend less time looking surprised.

The pattern keeps repeating

Screwworm is the lede, but not the only warning.

Avian flu supplied the household version of the lesson. Since 2022, highly pathogenic avian influenza has affected more than 166 million birds in the United States. That is a national food-price event with feathers on it. Birds are culled, barns go empty, producers wait to restock, and families meet the failure later in the egg aisle. USDA’s 2025 response cost $1 billion to fight the disease, protect poultry producers, and bring down egg prices. There is the arithmetic of neglect: a virus moves through barns, and the Treasury follows with a shovel.

Foot-and-mouth disease gives the trade version. In January 2025, Germany confirmed its first outbreak in nearly 40 years, not across a whole national herd but in water buffalo outside Berlin. The market did not shrug. Veterinary certificates became unusable for many exports outside the European Union, and German meat and dairy shipments suddenly faced severe restrictions. One case was enough to remind buyers that they do not merely purchase beef, milk, hides, or pork. They purchase trust in the system that certifies them.

The 2001 United Kingdom foot-and-mouth outbreak cost an estimated $9.2 billion and led to the slaughter of 6.24 million animals. More than half the total cost came not from the farmyard itself but from restrictions on rural tourism and recreation. That is how these events behave when early detection, clear authority, and adequate resources fail. The disease enters through animals; the damage leaves through every open door in the economy.

The common thread is neglected maintenance: surveillance allowed to fade, response capacity treated as waste, laboratories and inspectors asked to do more with less, and diplomatic channels left to stiffen until the day they are needed.

Diplomacy before disease

The best outbreak response begins before the outbreak.

That requires boring systems, which is one reason they are politically vulnerable: 

• Shared surveillance data. 
• Border protocols.
• Veterinary laboratories. 
• Sterile insect production. 
• Emergency response plans. 
• Animal movement documentation. 
• Regional notification rules. 
• Vaccination capacity. 
• Producer education.
• Transparent reporting. 
• Working relationships between agencies that trust each other.

This is what competent diplomacy looks like in food systems.The daily work of keeping technical channels open so that a pest in one country does not become a crisis in another.

The United States should treat this as a national food-supply priority. It should fund the sterile-fly infrastructure needed to contain screwworm. It should strengthen animal-health surveillance at the border and inside livestock-producing regions. It should support Mexico, Panama, and Central American partners in suppression efforts, because helping them contain the pest is not charity. It is prevention.

A country that waits for the parasite to cross the line has already misunderstood the line.