Arizona border to reopen to cattle, despite screwworm detection in Sonora

The U.S. Department of Agriculture says the Arizona border will still reopen to cattle on Monday, even after the first case of the New World screwworm was detected in the Mexican state to the south, Sonora.

USDA says it has no plans to change the Douglas, Arizona, cattle port reopening, despite the detection of the flesh-eating parasite in Sonora this week. The case was confirmed in the southern part of that state, nearly 300 miles from the border.

Douglas will become the first crossing point on the U.S.-Mexico border to let livestock through in more than a year, as the United States phases out the ban in place to protect against the New World screwworm.

The parasite burrows into the flesh of warm-blooded animals and can be deadly if left untreated. The United States officially eradicated the pest in the 1960s. Its recent arrival in Texas puts the country’s already low cattle herd at risk and threatens to drive up beef prices.

USDA said in a statement that the system it’s built up over the past 18 months since the parasite was first detected in southern Mexico is “coordinated, [and] highly sophisticated.”

Since then, the United States and Mexico have monitored thousands of insect traps to track the New World screwworm and have invested in increased production of sterile New World screwworm flies. Those flies mate with regular screwworm to dwindle the population and can be dispersed to prevent or respond to cases.

Sonora says 360,000 sterile New World screwworm flies were released in the area around the recently detected case in the south of the state.

Mexico and the United States have also beefed up inspection protocols for the cattle that are set to start crossing on Monday. USDA said those protocols include “enhanced surveillance, rapid diagnostic capacity, pre-treatment processes weeks in advance, layered inspections before and at the port, sophisticated communication and coordinated response protocols designed to protect American agriculture.”

There have been more than 40 cases of New World screwworm in Texas since it crossed the U.S.-Mexico border earlier this summer. Arizona has so far remained screwworm-free.