U.S. Department of Agriculture officials detected the New World screwworm parasite in a calf in Texas earlier this week [1, 2].
The discovery marks the return of a flesh-eating parasite that had been largely eradicated from the country for decades. The re-emergence poses a significant threat to the livestock industry, particularly cattle producers, and raises concerns regarding potential human exposure [1, 5].
The parasite, known scientifically as *Cochliomyia hominivorax*, was found in cattle located near the U.S.-Mexico border [2, 3]. This is the first time the pest has been detected in U.S. livestock since 1966 [2], representing a gap of 60 years [3].
Officials said the parasite likely crossed the border following recent outbreaks in northern Mexico [5]. In a related development, a flesh-eating parasite was also found on a goat located 25 miles south of the U.S. border in Mexico's Coahuila state [6].
Unlike many other fly species, the New World screwworm does not feed on dead tissue. Instead, it invades living flesh, creating wounds that can lead to severe infection or death if left untreated [1, 5]. The USDA is monitoring the situation to prevent the parasite from spreading further into the interior of the country.
Agricultural experts are now working to contain the infestation. The presence of the parasite in Texas suggests that the biological barriers and eradication efforts established over the last several decades may be facing new challenges due to regional outbreaks in neighboring territories [5].
“The discovery marks the return of a flesh-eating parasite that had been largely eradicated from the country for decades.”
The return of the New World screwworm after 60 years indicates a breach in the biological security zone that previously protected U.S. livestock. Because the parasite targets living tissue rather than necrotic flesh, it can cause rapid deterioration in healthy animals. This creates an immediate economic risk for the beef and dairy industries and may necessitate a return to large-scale eradication programs along the southern border to prevent a wider epidemic.
