Flesh-eating parasites target America. How close is Ohio’s screwworm?

These flies are not like their relatives that feed on dead and decaying animals. No, the flesh-eating carnivores of these parasitic worms prefer to feed on live animals such as cattle, horses, and pigs, and they can be deadly.

Another case of New World screwworm was recently stopped from entering the United States at a quarantine facility in Florida.

And people are not immune. A traveler returned to the United States last summer carrying the parasite from Central America.

Magnets penetrate through open wounds and mucous membranes. According to the Animal and Plant Health Inspection Service, they use “sharp mouth hooks” to bite, or screw, into animal flesh. This is how the new world got its name screwworm.

Is the New World screwworm in the United States? How close is it to Ohio? Here’s what to know.

‘Serious threat’ to US agriculture: How the USDA is Preparing for New World Screwworms

New World Screwworm Case Found at Florida Facility

According to the Florida Department of Agriculture and Consumer Services, screwworm larvae were found earlier this month in a horse imported from Argentina that was undergoing routine and required testing at an approved Department of Agriculture import facility in South Florida.

No detection of NWS larvae outside the quarantine facility. The affected horse was treated, and out of an abundance of caution, the agency said in a statement that all cohort horses at the facility were also examined and treated.

“There have been no detections of New World screwworm in any animals in Florida. The detection at the USDA import facility was handled professionally and according to existing protocols to ensure the US is free of this devastating pest,” state veterinarian Dr. Michael Short said in a statement.

Infected horses were to be quarantined until they were retested and found free of parasites.

Human screwworms: A deadly cattle screwworm parasite has been found in a patient in the US. what to know

Is the New World screwworm in the United States or Ohio?

According to the Centers for Disease Control and Prevention, the pest was eradicated in the United States in the 1960s, in Mexico in the 1970s, and in most of Central America by the early 2000s, USA Today reported.

However, the CDC said in October 2024 new cases were reported in Panama, Costa Rica, Nicaragua and Honduras. From there, it has spread north, with fears of the insects spreading north into the United States. Their movement has led to the U.S. banning imports of live cattle, horses and bison from southern border ports, USA Today reports.

ScienceAlert.com reported that there were 601 active animal cases in Mexico in January 2026, including eight in Tamaulipas – a state bordering Texas.

According to the USDA’s Animal and Plant Health Inspection Service, the New World screwworm does not currently exist in the US.

The closest it came to Ohio was a human case in Maryland from a traveler returning from El Salvador in 2025.

What is dangerous about the New World screwworm fly?

According to the CDC, NWS flies are the size of a common housefly and lay eggs “in open wounds or other exposed parts of the body in live, warm-blooded animals.” A wound as small as a tick bite can attract flies.

The eggs hatch and maggots hatch into the wound to feed on live flesh, the CDC says. As you might expect, biting maggots on living creatures is very painful.

After they feed, the larvae drop to the ground and bury themselves in it. They later emerge as adult screwworm flies, the CDC says.

New World Screwworms in Humans – What are the Symptoms?

According to the USDA, NWS infections are very painful. If you have an infection, you may notice maggots around or in open sores, or in your nose, eyes, or mouth. Symptoms may include:

• Unexplained skin lesions (sores or sores) that do not heal.

• Skin lesions or sores that worsen over time.

• Painful skin sores or ulcers.

• Bleeding from an open wound.

• Feeling the movement of larvae inside skin lesions or sores, nose, mouth, or eyes.

• Seeing magnets around or on an open wound.

• Foul odor from the affected area.

US plans to stop the spread of screwworms

The USDA’s plan to stop the spread of screwworm includes investing up to $100 million for innovations to find new ways to fight the worm and up to $750 million to create a facility in South Texas to sterilize the flies and fight the spread, USA Today reported in September 2025.

Releasing sterile flies to disrupt the reproduction of screwworms was a technique used to eradicate the pest in the 1960s. The hope is that those sterile flies will mate with wild ones, producing sterile eggs, experts said.

Another $21 million is being invested to renovate an existing fruit fly production facility in Metapa, Mexico to produce more sterile shrimp.

This article originally appeared in the Columbus Dispatch: Flesh-eating parasites target America. Is Ohio safe? More on the New World screwworm