Mexico’s agricultural health agency, Senasica, has started a sniffer-dog training program to help fight the rise of New World screwworm (NSW) populations.
The New World screwworm is an invasive fly that is sometimes called a “flesh-eating parasite.” Colin Woodall, CEO of the National Cattlemen’s Beef Association, told NPR that it is a serious threat to the U.S. meat industry. The fly lays eggs on livestock, like cattle. When the eggs hatch, the larvae burrow into the animal’s flesh, feeding on it. “The larva does exactly what the name suggests. It eats the animal from the inside out. It is a horrific parasite,” Woodall said.
Since late 2024, NSW populations have been moving north from South America and approaching the Mexico-Texas border. U.S. and Mexican government agencies are working together to prevent infestations.
Senasica’s Canine Trainer Center (Ceacan) has taken in rescue dogs for a three-month training program. The dogs are taught to detect NSW larvae in livestock wounds or agricultural products. Mayte Tontle, a Ceacan instructor, explained that the dogs train using “cow-sized equipment inside a greenhouse” to mimic the hot conditions where screwworms are usually found.
Not all rescue dogs make it through the program. Cesar Dangu, head of Ceacan, said that dogs who aren’t suitable are adopted by families, while energetic or unusual dogs are often perfect for detection work. “We also look for dogs that are calm, affectionate, and can live with people and other animals,” Dangu added.
Currently, six screwworm-sniffing dogs are working near the Chiapas-Guatemala border, where many infestations occur. The trained dogs usually work for eight years or until they turn 10. “I would say 99% of the dogs are adopted by their handler. There is a strong bond because of the love between them,” Dangu said.
The U.S. government is also taking steps to fight screwworms. A fly-dispersal facility in Edinburg, Texas, costing $8.5 million, helps the USDA detect, control, and eliminate the pest. Another $21 million has been invested in a facility in Metapa, Mexico, which produces 60 to 100 million sterile male screwworm flies. These males mate with females, but no eggs hatch, helping to stop the spread of NSW.
