Colorado has activated its New World Screwworm emergency response plan after the parasite was confirmed in Zavala County, Texas, in a 3-week-old calf with an infested umbilical area — marking the first confirmed case in the United States.

Governor Jared Polis and the Colorado Department of Agriculture's State Veterinarian's Office announced the activation, with the State Veterinarian leading Colorado's One Health response. The Texas Animal Health Commission and the U.S. Department of Agriculture are conducting a response that includes increased trapping of flies, releases of sterile New World Screwworm flies, and increased surveillance in wildlife.

"The health and safety of our cattle, food supply, and agriculture community is vital and we urge care and vigilance for our producers around the state," said Governor Polis. "Colorado is taking action to ensure readiness for the potential arrival of New World Screwworm in our state and are committed to giving the best guidance and information available to protect producers and their cattle. I have been briefed and am monitoring the situation very closely and evaluating any next steps needed."

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The New World Screwworm does not pose a food safety risk, and the U.S. food supply remains safe.

"Colorado has been diligently preparing for the eventuality of a New World Screwworm detection in the United States and we have a response plan ready," said Colorado State Veterinarian Dr. Maggie Baldwin. "We are working closely with our livestock industry partners to minimize the impacts of this detection on our livestock industries."

Key elements of Colorado's response plan include producer education, distribution of testing kits if needed, potential movement restrictions on animals from infested zones, and coordination with the Colorado Department of Public Health and Environment and Colorado Parks and Wildlife.

"While this detection in Texas is concerning, there is no reason to panic," said Erin Karney Spaur, Executive Director of the Colorado Cattlemen's Association. "Producers should remain vigilant, monitor livestock closely, and contact their veterinarian if they observe unusual wounds or signs of infestation."

"As this situation unfolds, we are encouraging producers to remain calm and continue operating as usual while remaining vigilant about their livestock," said Travis Grant, Chief Executive Officer for the Colorado Livestock Association.

Screwworms are parasitic fly larvae that feed on living tissue, causing extensive and potentially life-threatening damage. The flies are attracted to open wounds — from tick bites to dehorning wounds — where they lay eggs. The larvae then burrow into wounds, feeding on living tissue in a process called myiasis.

Screwworm myiasis is a reportable condition in Colorado in both animals and people. Veterinarians, producers, animal owners, and diagnostic laboratories must report any suspected case to the State Veterinarian's Office by calling 303-869-9130 or through the online Myiasis Reporting Form. There is currently no reason for concern for private horse or livestock owners, but producers should monitor their animals and contact their veterinarian if they observe any concerning myiasis infestations.

Updates will be posted at ag.colorado.gov/NWS. More information on the unified national response is available at Screwworm.gov.