Background on the New World Screw Worm
The New World screw worm, scientifically known as Cochliomyia hominivorax, is a significant livestock pest that can infest cattle, wildlife, and in rare cases, humans. The larvae of the screw worm fly penetrate animal skin, causing severe damage and often fatal consequences.
USDA Suspension of Mexican Cattle Imports
In response to the spread of this pest northward into Mexico, the United States Department of Agriculture (USDA) indefinitely suspended cattle imports from Mexico earlier this month.
USDA’s Plan to Resume Imports
Rosemary Sifford, the USDA’s chief veterinarian, stated that the US might resume Mexican cattle imports by the end of the year, pending further monitoring and risk assessment.
“It’s hard to pinpoint an exact date, but we are confident that the imports will resume safely before year-end, barring any drastic changes,” Sifford told Reuters during the World Animal Health Assembly in Paris.
Recent Developments
No new cases of the screw worm have been detected north of a location identified two weeks ago, approximately 700 miles from the US-Mexico border, according to Sifford.
A USDA mission is scheduled to visit Mexico in the coming days, as announced by Mexico’s Agriculture Ministry.
USDA’s Efforts Against Highly Pathogenic Avian Influenza
Sifford also mentioned that the end of the year represents the “ultimatum” for controlling the spread of highly pathogenic avian influenza, commonly known as bird flu, among dairy cows.
This virus has claimed over 173 million poultry, turkey, and other bird lives in the US since 2022 and has infected more than 1,000 dairy herds since 2024, according to USDA data.
Approximately 70 individuals in the US have tested positive for the virus since 2024, primarily agricultural workers, as reported by the Centers for Disease Control and Prevention.
Current Status of Bird Flu in Dairy Herds
“The only new lactating herd cases we’re seeing currently are in states with existing affected herds, and they are strongly linked to biosecurity issues,” Sifford explained.
“I’m uncertain if a complete halt will occur by this northern hemisphere summer, but we are making significant progress.”
Key Questions and Answers
- What is the New World screw worm? It’s a livestock pest (Cochliomyia hominivorax) that can infest cattle, wildlife, and rarely, humans. Its larvae penetrate animal skin, causing severe damage and often fatal consequences.
- Why did the USDA suspend Mexican cattle imports? The suspension was due to the northward spread of the New World screw worm pest into Mexico.
- When might the US resume Mexican cattle imports? According to USDA chief veterinarian Rosemary Sifford, imports could resume safely before the end of the year, pending further monitoring and risk assessment.
- What is the current status of highly pathogenic avian influenza in dairy herds? While the virus has caused significant losses among poultry and other birds, recent cases in dairy herds are primarily linked to biosecurity issues in affected states.
