Dr. Lora Bledsoe came to R-CALF USA with a message that was both practical and chilling: New World screwworm is not just an animal health issue. It is a border security issue, a food security issue and a national security issue.
Bledsoe, a veterinarian serving in the Department of Homeland Security’s Office of Health Security, spoke to ranchers about the connection between the reemergence of New World screwworm and illicit cattle movement tied to cartel activity in Mexico and Central America.
It was one of the most direct explanations yet of why a livestock parasite belongs in the same conversation as border enforcement, food supply chains and organized crime.
New World screwworm is not actually a worm. It is an invasive fly that lays eggs in open wounds. The larvae hatch into maggots that feed on living flesh, unlike most maggots that feed on dead tissue. The pest can affect any warm-blooded animal, including cattle, horses, sheep, goats, dogs, cats, wildlife and humans.
“This can start with wounds as small as a tick bite or an injection site,” Bledsoe said.
Umbilical sites in newborn calves, castration wounds, branding wounds, ear tagging sites, vaccine sites and mucous membranes can all provide entry points. If untreated, infestations can cause severe pain, tissue destruction, infection and death.
The United States eradicated New World screwworm decades ago through a sterile fly release program. Now it has moved north again through Central America and Mexico and has been confirmed in Texas.
The control strategy remains the same: overwhelm wild populations with sterile male flies. Female flies mate only once. If they mate with a sterile male, their eggs are not viable, breaking the reproductive cycle.
Bledsoe said historic estimates suggest it would take roughly 500 million sterile flies per week to defend the border and push the pest back. Current production is far below that level, though additional facilities in Mexico and Texas are being developed.
The economic stakes are enormous. If New World screwworm became established in the United States, Bledsoe said losses could reach billions of dollars annually through animal death loss, production losses, treatment costs, movement restrictions and trade impacts.
But the part of the presentation that grabbed the room was her explanation of “narco ranching.”
Bledsoe described narco ranching as a cartel-linked practice used in parts of Central America and Mexico to launder drug profits, secure territory along trafficking routes, conceal illegal activity and move money, drugs, weapons and people.
Cattle, she said, are part of that system.
Mexican authorities estimate hundreds of thousands of head are smuggled annually through Central America into Mexico. Those animals may be moved under fraudulent ear tags and veterinary documents, then mixed into legal herds.
That matters because smuggled cattle bypass normal animal health inspections. If infected animals are moved illegally, diseases and parasites can travel with them.
Bledsoe said that illicit cattle movement is considered a major reason New World screwworm spread through Mexico faster than expected.
She stopped short of saying narco ranching caused the current U.S. cases. Federal officials are still tracing how the parasite entered Texas. Wildlife, weather patterns and legal or illegal animal movement are all being examined.
But the broader warning was clear: animal disease surveillance breaks down when cattle move outside lawful channels.
“This illegal cattle chain supports the drug economy and increases the risk of animal disease transfer,” she said.
Bledsoe also explained why livestock trailers are attractive tools for smugglers. They are dirty, crowded and difficult to inspect. Manure and urine can interfere with detection dogs, and trailers offer multiple places to conceal people, currency, drugs or weapons. In some cases, animals themselves may be used to hide contraband.
For ranchers, the immediate responsibility is vigilance.
Animals should be monitored closely for wounds containing eggs or maggots, irritated behavior, head shaking, licking, chewing, reduced movement or swelling. Any suspicious wound should be reported quickly to a local veterinarian or state animal health official.
If larvae are found, Bledsoe said producers should try to cover the wound to prevent larvae from dropping to the ground, collect samples in a leakproof container if possible, and hold the animal where officials can inspect it.
She urged producers to develop prevention plans with their veterinarians before the parasite reaches their area. Approved medications and emergency-use treatments may be part of that plan, but timing, withdrawal periods and correct use need veterinary guidance.
Ranchers also asked about rodeo stock, pets, wildlife and colder states. Bledsoe said companion animals are a real concern, particularly because dogs and cats can travel long distances with fewer controls than livestock. Rodeo animals moving from affected regions may face additional state requirements depending on destination.
Cold weather may limit establishment in northern states, but summer movement of flies or infected animals remains a concern.
For DHS, the issue sits squarely inside its mission. Food and agriculture are part of the nation’s critical infrastructure. A major animal disease or pest outbreak would not only affect ranchers. It would affect food supply, rural economies, trade, border enforcement and public health.
That is why Bledsoe said DHS is working with USDA, state animal health agencies, law enforcement and industry partners to strengthen preparedness.
For ranchers, her message was blunt: this is not just another government briefing. It is a live threat moving through real cattle, real borders and real criminal networks.
The screwworm fight will be fought with sterile flies, veterinarians, border agents, ranchers and early reporting.
And once again, rural producers are on the front line of national security.