New Mexico has become the first state in the country to be released from a New World screwworm-infested zone since the pest returned to the United States this summer. The Agriculture Department's Animal and Plant Health Inspection Service approved the release on August 30, ending the movement restrictions that had applied to livestock and pets in the affected area.
The immediate effect is practical rather than medical. Lifting the zone removes screwworm-related requirements on the domestic movement of animals from that area, which means producers and pet owners in the affected part of New Mexico can resume normal movement within the state.
The action rests on a specific record. New Mexico detected its first and only case, in a dog in Lea County, on June 7, and no additional cases have been found since. State and federal experts confirmed the state met the requirements in the agency's response playbook for zone release.
One Dog, One Zone, and the Standard for Closing It
The New Mexico case never grew into a cluster, which is why the zone could close.
"New Mexico's animal health officials have been exceptional partners throughout our response," said Dudley Hoskins, USDA Under Secretary for Marketing and Regulatory Programs, in the agency's announcement. He credited state and federal collaboration for keeping case numbers low.
The release followed a recommendation from state veterinarian Dr. Samantha Holeck and the New Mexico Livestock Board. Response activities inside the zone had included domestic animal movement requirements and animal inspections.
MedicalDaily reported earlier this month that Texas added a new infested zone in Terrell County after a detection in sheep, with the national count at 45 confirmed detections and only five still active. New Mexico's release is the first movement in the other direction.
Texas Is Still the Live Front
The national picture is lopsided and has been since the pest was confirmed in a calf in Zavala County, Texas, on June 3. Nearly every confirmed U.S. detection since has been in Texas, with New Mexico's dog the single exception.
Case counts have slowed sharply. June ended with 30 confirmed cases, 29 of them in Texas. July added 14 more, all in Texas. As August closed, three cases had been reported in the Big Bend area along the Rio Grande, involving two sheep and one goat, according to Oklahoma Farm Report, which tracks the federal dashboard. No cattle case was confirmed in the United States during August.
Detection numbers should be read with a caveat that cuts in both directions. USDA has expanded surveillance with increased fly trapping along the border and stepped-up animal inspections, so more looking produces more findings. A rising cumulative count does not by itself show accelerating spread, and a falling monthly count is encouraging without being proof of containment. A congressional review of the response also notes that individual case investigations remain open and that confirmed totals may change as cases are verified.
The pest remains widespread to the south. CDC reports that Mexico and Central American countries have logged more than 209,400 animal cases and about 2,500 human cases since the northward spread began. Proximity is the whole argument for maintaining trapping and inspection even during a quiet month, because the pest does not need to establish a population in the United States to cause damage. It only needs a fly to find an untreated wound.
Border Trade Reopened While the Zone Was Closing
The zone release lands in the same week as a separate federal decision that pulls in the opposite direction.
USDA reopened the Douglas, Arizona port to Mexican cattle imports on August 24, the first step in a phased reopening of southern ports that the department says is contingent on satisfactory progress against joint action plan milestones. The agency has said it will evaluate that reopening before considering the Santa Teresa and Columbus ports in New Mexico.
The Human Question, Answered Plainly
No locally acquired human cases have been reported in the United States during this outbreak. That is the headline fact for readers who do not own livestock. The one U.S. human case tied to the regional spread was travel-associated, confirmed in August 2025 in a person who had returned from El Salvador.
Screwworm can infest people, which is why the CDC has kept clinicians in border states alert, but the agency describes the risk to people as very low, and infestation typically involves untreated open wounds in areas with active fly populations. Households in Texas and New Mexico with outdoor pets have a more realistic concern than households worried about themselves.
The practical advice from USDA is the same for a rancher and a dog owner. Check animals for draining or enlarging wounds and signs of discomfort, and look for larvae or eggs in or around the nose, ears, genitalia, or the navel of newborn animals. A wound as small as a tick bite can attract a female fly. If you find larvae in a wound, contact a veterinarian immediately rather than treating it yourself, and report it to the state animal health authority. Keeping open wounds clean and covered is the main protective step for people in affected areas.
Cost is a real factor for producers rather than for households. Treating an infested animal requires veterinary attention and approved wound products, and animals inside a zone face movement limits that can delay sales. Lifting the New Mexico zone removes that second cost for producers in the affected area.
What remains unresolved is whether the summer slowdown holds through fall, when cooler weather typically reduces fly activity, and whether the reopened port changes the introduction risk. APHIS updates its detection dashboard regularly. MedicalDaily will report new infested zones, further zone releases, any detection outside Texas and New Mexico, and any locally acquired human case.
Key Questions Answered
What changed? USDA approved the release of New Mexico's only screwworm-infested zone, lifting movement restrictions on livestock and pets from that area.
Why was the zone released? No new cases were detected after the state's first and only confirmation, in a dog, on June 7, and the state met federal requirements for release.
Is the outbreak over? No. Texas continues to report detections, most recently in the Big Bend area along the Rio Grande, and surveillance continues in both states.
Have any people been infested in the United States? No locally acquired cases have been reported. One travel-associated case was confirmed in 2025 in a traveler returning from El Salvador.
What should pet and livestock owners look for? Draining or enlarging wounds, signs of discomfort, and larvae or eggs around the nose, ears, genitalia, or a newborn animal's navel.
How can people protect themselves? CDC advises keeping open wounds clean and covered in areas where screwworm flies are present, regardless of how small the wound is.
Is the border open to cattle again? Partially. The Douglas, Arizona port reopened under inspection protocols. No reopening date has been announced for the two New Mexico ports.
