The United States has confirmed a case of the New World screwworm fly in South Texas, a flesh-eating parasite not seen in the country since 1966 [3].
The re-emergence of this parasite threatens the U.S. cattle industry, which is valued at approximately $113 billion [1]. Because the larvae can be fatal to livestock, the detection triggers urgent concerns regarding the stability of the domestic food supply, and animal health.
Officials identified the infection in a three-week-old calf [2]. The case was detected in early 2024 in La Pryor, a town located near the U.S.-Mexico border [2, 3].
The New World screwworm causes myiasis, a condition where the fly's larvae burrow into the living tissue of warm-blooded animals. Unlike other flies that feed on dead tissue, these parasites eat healthy flesh, creating deep wounds that can lead to systemic infection or death if left untreated [1, 4].
This is the first time the parasite has been confirmed in the U.S. in about 60 years [3]. The long absence of the pest followed extensive eradication efforts designed to protect agricultural productivity, and livestock welfare across the continent.
Agricultural experts and government agencies are monitoring the border region to prevent the parasite from spreading. The high value of the cattle industry makes the containment of this specific parasite a priority for federal authorities [1, 4].
“The New World screwworm fly has reappeared in South Texas, posing a threat to the nation's multibillion-dollar cattle industry.”
The return of the New World screwworm represents a significant biosecurity breach. Because the parasite targets living tissue, it can spread rapidly through herds, potentially causing massive economic losses and necessitating aggressive containment measures along the southern border to prevent a wider epidemic.
