The United States will reopen its first southern livestock port to Mexican cattle on August 24, ending a border closure that has been in place for about a year. The reopening in Douglas, Arizona comes while the New World screwworm remains confirmed in animals in Texas and New Mexico, and it is the clearest sign yet that federal officials believe the parasite's northward push has been slowed rather than stopped.
The decision is a judgment call with a supply chain attached. Mexican feeder cattle are a key input to American beef production, and closed ports have squeezed supply amid high retail beef prices. Reopening one crossing does not fix that, but it is the first movement in more than a year.
For households, the connection runs through the grocery bill rather than the medicine cabinet. Screwworm does not make meat unsafe. It infests living animals, and federal inspection is designed to keep infested animals out of the food supply. The consumer stake here is cattle supply and price, not contamination.
The Terms Attached to the Douglas Reopening
The Animal and Plant Health Inspection Service has identified Sonora and Chihuahua as the lowest-risk Mexican states for screwworm, citing established inspection programs and geographic distance from southern Mexico, where most cases are concentrated. Douglas borders Sonora, and the nearest active case is roughly 325 miles away, detected on July 22.
According to the agency's current status page, APHIS will evaluate how the initial reopening performs before considering Santa Teresa and Columbus, New Mexico, for live cattle, bison, and horses. The timeline is explicitly flexible, and USDA says the opening of ports may be paused if it identifies increased risk in Sonora or Chihuahua through post-opening audits or other information.
USDA announced the phased reopening plan in late July, conditioning it on Mexico meeting milestones in a joint action plan. Every animal entering through the reopened ports will undergo a full USDA inspection for signs of infestation. Agriculture Secretary Brooke Rollins framed the year-long closure as a difficult but necessary step to control the spread in Mexico and protect the American livestock industry.
The Detection Count Has Not Moved in a Week
As of August 10, USDA had confirmed 45 screwworm detections in the United States since the outbreak began, including 44 in Texas and one in New Mexico, according to a Congressional Research Service report. The first detection of this outbreak was confirmed on June 3 in a three-week-old calf in Zavala County, Texas, with larvae identified in the animal's umbilical area. The single New Mexico case, in Lea County, involved a dog and was both the first detection outside Texas and the first in a companion animal.
MedicalDaily reported earlier this month that Texas established a new infested zone in Terrell County after screwworm was confirmed in sheep, with the cumulative count at 45 and only five cases still active. That the total has held while a port reopens is the operative fact. Containment in this context does not mean zero detections. It means confirmed cases are being closed out faster than new ones are emerging, and that the geographic footprint has remained narrow. It also reflects more intensive looking, since the USDA has expanded surveillance across affected areas using fly trapping, drone flights, and trail cameras.
Separately, USDA has committed $25 million toward a dispersal facility for sterile flies in Arizona. Sterile fly production remains the central constraint on the whole response, and industry groups have described current output as insufficient for an outbreak of this size.
The eradication method itself is old and well proven. Releasing sterilized male flies in sufficient density collapses a wild population over successive generations, which is how the United States eliminated the pest domestically by 1966. The method only works at scale, which is why production capacity, not scientific uncertainty, is the limiting factor in this response.
The Human Health Picture Stays Narrow
Screwworm can infest people, but it is uncommon. The CDC says the risk of screwworm in people remains very low and reports no human infestations acquired inside the United States, according to the agency's situation summary. One case was confirmed in August 2025 in a person who returned to the United States after traveling to El Salvador. That case was investigated with the Maryland Health Department; targeted trapping around the affected area returned no positives, and no secondary cases were identified.
The people who face real exposure are livestock producers, ranch workers, veterinarians, wildlife managers, and pet owners inside or near the Texas quarantine zones. Anyone with an open wound who spends time outdoors in affected counties of South and Southwest Texas has a small but genuine reason to pay attention.
The warning sign in animals is a wound that keeps enlarging, drains, or contains visible larvae, often accompanied by an unusual odor and signs of discomfort. USDA advises checking the nose, ears, genitals, and the navel of newborn animals. In people, the concern is a wound that fails to heal normally, appears to grow, or contains moving material. That warrants prompt medical attention rather than home treatment.
Reasonable Steps for Ranch Families and Pet Owners
Households in affected areas should inspect livestock and pets daily during warm months, clean and cover fresh wounds promptly, and avoid moving animals out of an infested zone without the required inspection. Suspected cases in Texas should be reported promptly to a Texas Animal Health Commission regional office or the commission's toll-free line at 1-800-550-8242. Owners in other states should contact a veterinarian and their state animal health official.
Nobody needs to change grocery habits. USDA has consistently stated that the food supply is not affected and that inspection processes are designed to identify and exclude infested animals.
Several things remain unresolved. USDA has not published a threshold that would trigger a pause in reopening; sterile fly production capacity remains below what the outbreak's scale would require, and the number of undetected infestations on open rangeland between confirmed cases is unknown. The Douglas reopening takes effect on August 24, and APHIS says it will assess results before considering the two New Mexico ports. MedicalDaily will track the detection dashboard and any changes to the port schedule.
Key Questions Answered
What is changing on August 24? USDA will reopen the Douglas, Arizona port of entry to livestock trade with Mexico. It is the first southern port to reopen after roughly a year of closure.
Is the outbreak over? No. USDA had confirmed 45 U.S. detections as of August 10, with 44 in Texas and one in New Mexico. Officials describe the spread as contained, not eliminated.
Is beef safe to eat? Yes. Screwworm infests living animals and is not a food safety issue. Federal inspection is designed to keep infested animals out of the commercial supply.
Can people get screwworm? Rarely. CDC describes the risk to people as very low and reports no infestations acquired inside the United States. One case in 2025 involved a person returning from El Salvador.
Who should be checking animals daily? Livestock producers, ranch workers, and pet owners in or near the Texas quarantine zones, especially around fresh wounds and newborn animals.
Could the reopening be reversed? Yes. USDA says the schedule is flexible and openings may be paused if post-opening audits or new information show increased risk in Sonora or Chihuahua.
Why does sterile fly supply keep coming up? Sterile insect release is the core eradication tool, and industry groups describe current production capacity as insufficient for an outbreak of this size. USDA has committed $25 million toward a new Arizona dispersal facility.
