There have been no reports of locally acquired human screwworm infestations in the United States, according to the CDC's situation summary. That is the most important fact in a story widely misread as an outbreak of flesh-eating parasites infesting Americans.
The single US human case, confirmed in August 2025, was travel-associated, in a patient who had returned from El Salvador. The animal outbreak is real. USDA confirmed the first domestic animal case of the current outbreak on June 3, 2026, in Texas, and detections have since been recorded in additional Texas counties and in New Mexico.
What is new is that the animal count has fallen far faster than the response expected. Only four animal detections were recorded in August, none in cattle, compared with 30 in June, according to USDA dashboard figures reported by NOTUS. USDA attributes the drop to its control playbook working. Current and former officials quoted in that reporting are skeptical, partly because trapping has caught no wild flies at all.
The Federal Position on Human Risk
Screwworm is a parasitic infestation, not a contagious infection. It occurs when the fly lays eggs in a wound or body opening, and the larvae feed on living tissue. It is not passed from person to person, which is why a rising animal count does not create person-to-person risk.
The regional picture explains the vigilance. Central American countries and Mexico have reported more than 209,400 animal cases and more than 2,600 cases in people. People at higher risk live in or travel to areas where flies have infested animals, particularly anyone with an open wound, a narrow group that does not describe most US households.
A Falling Case Count Experts Are Struggling to Explain
The August figure of four broke the outbreak's trajectory, and it arrived while the pest was still advancing in Texas and while Mexico and Central America continued reporting high numbers. A former longtime USDA official told NOTUS the pattern is very strange and does not make much sense biologically.
"Zero cases in wildlife is unexplainable to me," Texas Agriculture Commissioner Sid Miller told NOTUS. He said he and colleagues had caught insects they believed were screwworm, only for USDA testing to come back negative, and questioned whether the wildlife cameras being used for surveillance can reliably identify open wounds on animals. A former USDA official who oversaw the screwworm response made a similar point, saying the cameras are not catching anything.
Two explanations remain open. Control efforts, including sterile fly releases, may be suppressing the population, or surveillance may be missing flies that are present. Neither has been established, so the low count is a figure under scrutiny rather than an all-clear. USDA maintains a public detections dashboard logging confirmed cases by county and species, which is the reliable place to check a specific county.
Pets, Travel and the New Prevention Authorization
The clearest household development came from the FDA, which issued an emergency use authorization for Capstar tablets and revised the authorization for generic nitenpyram tablets to cover prevention as well as treatment in dogs, puppies, cats and kittens weighing at least two pounds and aged at least four weeks. The generic product had been authorized in June for treatment only.
Timothy Schell, director of the FDA's Center for Veterinary Medicine, said in the agency's announcement that multiple products had been authorized or conditionally approved for treatment in dogs and cats, but "none were for prevention, until today." MedicalDaily previously reported on an earlier authorization covering ivermectin for horses.
The FDA notes that most US dogs and cats remain at low risk because of where they live. The animals worth monitoring are pets that live in, travel to, or return from areas where infestations have been identified, and certain countries south of the border. Pets and service animals arriving from affected countries must meet USDA and CDC import requirements.
Signs, Reporting and the Limits of Current Data
In animals, the signs are visible maggots or a foul odor in a wound or body opening such as the eyes, ears, nose or mouth, and an infested pet needs immediate veterinary care. Veterinarians should report suspected cases to their state animal health official and USDA, and clinicians who suspect a human infestation should notify their state health department immediately.
Households do not need to change travel plans, avoid beef, or treat pets that never leave a low-risk area. The proportionate steps are keeping wounds clean and covered, checking pets after travel to affected regions, and confirming import paperwork before bringing an animal across the border.
Two things remain unconfirmed: why traps have caught no wild flies, and whether the August decline holds through fall. Sterile fly release, which floods an area with males that cannot reproduce, is central to the eradication plan and works slowly by design. MedicalDaily will monitor the USDA dashboard, the CDC's summary, and any confirmed human case.
Key Questions Answered
Have any Americans caught screwworm inside the United States? No. The CDC reports no locally acquired human infestations. The one US human case, confirmed in August 2025, was acquired during travel.
Can screwworm spread from person to person? No. It is a parasitic infestation caused by fly larvae in a wound or body opening, and it is not passed between people.
How many animal cases has the United States had? USDA confirmed the first animal case of the current outbreak on June 3, 2026, and has logged detections across multiple Texas counties and in New Mexico. Only four detections were recorded in August, none in cattle, compared with 30 in June.
Why are experts questioning the low numbers? Trapping has caught no wild flies, and no cases have appeared in wildlife or feral animals. Officials, including the Texas agriculture commissioner, say that is difficult to explain.
What should pet owners watch for? Maggots or a foul odor in wounds or body openings. Seek immediate veterinary care if infestation is suspected, and check USDA and CDC import requirements before bringing an animal from an affected country.
