The U.S. Department of Agriculture’s (USDA) National Veterinary Services Laboratories has confirmed a new case of NWS in a calf in La Salle County, Texas. The USDA and the Texas Animal Health Commission (TAHC) have expanded surveillance and response measures in the area. 

New World screwworm is a parasitic fly that causes severe, potentially fatal infestations by feeding on the living tissue of warm-blooded animals. Quick detection, treatment, and reporting are vital to safeguarding livestock, wildlife, and pets. 

USDA and TAHC are conducting a coordinated response that includes: 

• Joint epidemiological investigations and case tracing 
• Additional surveillance, testing, and trapping in the affected areas 
• Releasing sterile insects and adjusting these operations as needed for the most effective coverage 
• Conducting outreach to animal owners  
• Ongoing coordination with local officials, veterinarians, ranchers, and community partners 

Guidance for Animal Owners and Veterinarians 

The most important thing animal owners can do is to know what to look for and how to report suspected cases of NWS. The USDA urges everyone in the area to check animals for: 

• Draining or enlarging wounds 
• Maggots or egg masses 
• Signs of discomfort 
• Lesions in body openings (nose, ears, genitalia, umbilical area) 

Anyone who suspects a screwworm infestation should immediately contact their veterinarian, state animal health official, or the USDA. Early reporting is essential to ensure animals receive prompt treatment so they fully recover.   

Though rare in people, anyone who notices a suspicious lesion should seek immediate medical care. 

Additional updates and resources are available at Screwworm.gov.   

Editor’s note: Current screwworm case counts can be found at https://www.aphis.usda.gov/animals/animal-health/livestock-and-poultry-disease/current-status/us-confirmed-cases-new-world