The screwworm threat covered in our previous post just escalated — and so has the federal response.
What’s Changed
On February 5, 2026, FDA issued an Emergency Use Authorization (EUA) for IVOMEC (ivermectin 1%) Injection as preventive treatment against New World Screwworm infestation in cattle. This is the first EUA for an over-the-counter injectable product authorized for this purpose.
One week earlier, Governor Abbott issued a statewide disaster declaration enabling full state resources for prevention and surveillance.
The EUA: What Veterinarians Need to Know
Product: IVOMEC (ivermectin 1%) Injection (Boehringer Ingelheim)
Authorized use: Prevention of NWS larvae (Cochliomyia hominivorax) infestation via subcutaneous injection
Dosing: Standard 200 mcg/kg (1 mL per 110 lbs body weight)
When to use:
- Within 24 hours of birth
- At castration
- Upon wound appearance
Exclusions:
- Female dairy cattle producing milk for human consumption
- Veal calves
Withdrawal: 35-day slaughter withdrawal
Important: This is approved for cattle only. Do not use off-label in other species (particularly dogs, where ivermectin toxicity risk varies by breed).
Why This Matters Now
No cases have been detected in the United States, but the threat is closer than it has been in decades:
- ~4,940 confirmed cases in Mexico as of early February 2026
- 714 active cases concentrated in Tamaulipas and Nuevo Leon—states directly bordering Texas
- The $15-30 billion U.S. cattle industry is at stake
The EUA provides a practical prevention tool where previously only post-exposure treatment was available.
Texas Response Resources
Governor Abbott’s January 29 disaster declaration activated the Texas New World Screwworm Response Team, a joint effort between:
- Texas Parks & Wildlife Department
- Texas Animal Health Commission
This enables expanded surveillance (including border traps), enhanced sterile fly releases, and streamlined coordination between state and federal agencies.
Practical Implementation
For Texas veterinarians and cattle producers:
- Stock IVOMEC Injection — it is now authorized for preventive use in high-risk scenarios
- Protocol timing — administer at birth, castration, or any wound occurrence
- Document administration — EUA products require tracking
- Continue surveillance — prevention does not replace the need to report suspicious wounds
For veterinarians outside Texas: the EUA applies nationally, but awareness is most critical in border states and for any cattle with potential exposure to Mexican animals or border areas.
Duration
The EUA remains effective until revoked or until HHS terminates the underlying NWS emergency declaration (originally issued August 2025).
Resources
- FDA EUA documentation: fda.gov/media/190966/download
- USDA APHIS Screwworm Program: screwworm.gov
- Texas Response Updates: gov.texas.gov
- Report suspicious cases: 1-866-536-7593
Key Takeaways
- FDA has authorized IVOMEC Injection for prevention — a significant shift from treatment-only options
- Texas disaster declaration puts full state resources behind surveillance and response
- No U.S. cases yet, but ~700 active cases sit just across the Rio Grande
- Timing matters: use at birth, castration, or wound occurrence — not after infestation
The U.S. eradicated screwworm in 1966. The coordinated federal and state response aims to keep it that way.
For background on NWS biology, clinical signs, and reporting requirements, see our original screwworm alert.