The last known outbreak of New World screwworm in Oklahoma occurred nearly 50 years ago, but animal health experts say the parasitic fly is no longer just a historical concern. As the pest continues to advance through Mexico, Oklahoma State University Extension is increasing education and surveillance efforts to ensure producers are prepared should the threat reach the United States.
Specialists with Oklahoma State University Extension say many producers today have never encountered New World screwworm, making awareness and early detection critical. The parasite poses serious risks to livestock, wildlife, pets, and even humans, though officials stress it does not present a food safety concern.
A High-Impact Animal Health Threat
New World screwworm is a zoonotic parasite capable of infecting all mammals. Female flies lay eggs in open wounds, sometimes as small as a tick bite. After hatching, the larvae feed on living tissue, causing rapidly worsening infections that can become fatal if left untreated.
Experts warn that untreated infestations can lead to death in as little as two weeks. Newborn animals face the highest risk, as the parasite can infect the umbilical area. In these cases, mortality can reach 100 percent without prompt treatment.
The insect’s scientific name, Cochliomyia hominivorax, translates to “man eater,” reflecting the severity of the damage it causes.
Why Early Detection Matters
Historically, the United States eradicated New World screwworm through the sterile male insect technique. This approach involved releasing sterilized male flies that prevent reproduction when they mate with females. While the method remains effective, experts note that reduced sterilization capacity following eradication has complicated current control efforts as the pest moves northward.
Because of this, Extension specialists emphasize that prevention and early response now play a central role in limiting potential spread.
Producers are encouraged to inspect animals regularly, monitor wounds closely, and treat injuries promptly. Common warning signs include visible maggots in wounds, irritation, head shaking, lethargy, depression, and a strong, foul odor.
Preparing Producers and Communities
OSU Extension has mobilized educators across all 77 Oklahoma counties to strengthen surveillance and response readiness. County educators have received training to recognize symptoms, collect samples, and submit them for diagnostic confirmation if a suspected case arises.
Samples can be analyzed at Oklahoma State University’s diagnostic laboratories in Stillwater, which are equipped to identify New World screwworm quickly and accurately.
Extension teams are also hosting producer meetings and outreach sessions to help establish relationships before an emergency occurs. Animal health experts stress that having an established relationship with a veterinarian is essential for rapid response—not only for screwworm, but for overall herd health.
Economic Stakes for Agriculture
An outbreak would have significant economic consequences for Oklahoma agriculture. The state’s beef industry, its largest agricultural sector, would be particularly vulnerable to livestock movement restrictions, increased treatment costs, and production losses.
Officials caution producers not to panic but to remain informed and proactive. Regular animal checks, prompt wound care, and awareness of reporting procedures remain the most effective tools for limiting risk.
Oklahoma State University Extension continues to share updates and educational resources, while additional tracking and information are available through the United States Department of Agriculture.
As conditions evolve, Extension specialists say preparedness and vigilance will be key to protecting livestock, wildlife, and companion animals across the state.
