New World Screwworm Detected in U.S. Traveler

August 24, 2025

A rare case of New World screwworm has been confirmed in a person traveling from abroad into Maryland, according to federal health officials.

The Centers for Disease Control and Prevention (CDC) quickly identified and treated the case, following established protocols. The individual was diagnosed upon arrival, and the incident was managed without complications.

A report from the director of communications for the Department of Health and Human Services said the case was in a patient who returned to the U.S. from travel to El Salvador and was confirmed by CDC through telediagnosis on Aug. 4, 2025. He said the risk to public health in the U.S. from this introduction is very low. The health status of the patient was not disclosed.

Colin Woodall, CEO of the National Cattlemen's Beef Association (NCBA), emphasized that there is no elevated risk to the livestock industry at this time. "The case was quickly identified and handled by the CDC in accordance with their protocols," Woodall said.

"We appreciate the diligence of human health authorities. This case was quickly addressed thanks to existing protocols, and we are thankful for the ongoing coordination between the CDC, state departments of health, state animal health officials, and USDA."

The New World screwworm, a parasite capable of causing severe and often fatal infestations in animals, was eradicated from the U.S. in 1966 after an extensive campaign. It remains present in parts of South America and the Caribbean, making constant vigilance critical.

Animal health officials stress that the swift response in this case highlights the effectiveness of surveillance and coordination efforts between human and animal health agencies in protecting both public health and America's livestock.

SHIFT IN MARKETS

DTN Livestock Market Analyst ShayLe Stewart said that the cattle complex opened to a grim reality Monday morning after an exceptionally strong week last week.

"Last week, fed cash cattle prices jumped $2 to $5 higher, the CME feeder cattle index reached a new all-time high of $350.18, and both the live cattle and feeder cattle contracts achieved new contracts highs as well," Stewart said. "But over the weekend, news broke from the CDC that a positive case of New World screwworm had been detected in a person traveling abroad into Maryland, which consequently drove prices sharply lower at Monday's start."

Stewart continued that Friday's USDA Cattle on Feed report also didn't help matters, as the report didn't show as steep of a year-over-year regression in placements as most analysts assumed it would.

"But more than anything, Monday's weakness is being driven by the news of the positive NWS case, and it's likely that an unsettled, uneasy tone lingers throughout the market for multiple days," she added.

Source: Western Ag Network, DTN & NCBA