U.S. Likely to Resume Mexican Cattle Imports by Year End, USDA Chief Veterinarian Says

By Sybille de La Hamaide

PARIS, May 28 (Reuters) – The United States will likely resume Mexican cattle imports by year-end, after a halt due to the spread in Mexico of the New World screwworm pest that can devastate livestock, the U.S. agriculture department’s chief veterinarian said on Wednesday.

Screwworm can infest livestock, wildlife, and in rare cases, people. Maggots from screwworm flies burrow into the skin of animals, causing serious and often fatal damage.

The USDA indefinitely suspended cattle imports from Mexico this month, citing the pest’s northward movement.

“We want to make sure that we’re comfortable that the way that they’re doing surveillance gives us a good picture of what our risk level is for the fly continuing to move north,” USDA’s chief veterinary officer, Rosemary Sifford, told Reuters on the sidelines of the World Organisation for Animal Health’s annual assembly in Paris.

“It’s hard to say exactly when, but (imports will resume) for sure before the end of the year, unless something really dramatically changes,” Sifford said.

No new cases of screwworm have been found farther north than one detected two weeks ago about 700 miles from the U.S.-Mexican border, Sifford said.

A USDA mission will travel to Mexico in the coming days, Mexico’s agriculture ministry said on Tuesday.

Sifford also gave the end of the year as a “very last” deadline for controlling the spread of highly pathogenic avian influenza, commonly called bird flu, in dairy cows.

The virus has led to the deaths of over 173 million chickens, turkeys and other birds in the United States since 2022 and infected more than 1,000 dairy herds since 2024, USDA data show. Seventy people in the U.S. have also tested positive, mostly farm workers, since 2024, according to the U.S. Centers for Disease Control and Prevention.

“The only new (dairy) cases that we are seeing at this point are in states where we already have herds affected and are very much associated with biosecurity problems,” Sifford said.

“I’m not sure if (a full halt) will happen by the summer, but we’re definitely on a steady path.”

For poultry flocks, the summer should be “quiet” for infections, with the number of outbreaks falling in recent weeks, Sifford said. Wild birds can transmit the virus to poultry flocks, which are then culled to contain outbreaks.

“We are not seeing introductions from wild birds, so we are expecting a quiet summer,” Sifford said.

(Reporting by Sybille de La Hamaide, aditional reporting by Tom Polansek in Chicago)