It Won’t Shock Anyone, But Flesh-Eating Worms Have Made their way into the US

A case of New World screwworm has been confirmed in South Texas, the U.S. Department of Agriculture announced Wednesday night. It marks the first breach of the US-Mexico border by carnivores, which have been on the rise across Central America for the past few years.

In a social media post Wednesday afternoon, the USDA revealed that the Texas sample was sent to the National Veterinary Services Laboratories (NVSL) in Ames, Iowa, to be tested for screwworm infection. Agriculture Secretary Brooke Rollins later tweeted that tests confirmed the infection, which was found in a three-week-old calf in Zavala County, Texas.

Talk of worm detection has been building this week, roiling the American cattle industry.

Although many animals, including humans, can become victims of this disease, the screwworm is more dangerous for livestock. Female worms lay hundreds of eggs in the wounds and openings of warm-blooded creatures, allowing their larvae to feast on living animals, causing deep, oozing, life-threatening ulcers. Although the screwworm was once found in the US, it was eradicated during the age control effort in the 1960s. The USDA estimates that keeping screwworms in the US has saved the livestock industry $900 million each year.

But the fly has broken control efforts in Central America and has been getting closer. On May 28, a case was found 25 kilometers from the border in a five-year-old goat in Coahuila, Mexico, according to the USDA. This case was one of many found in recent days, including a case in a calf 39 kilometers from the border, in Coahuila.

Disputed Acquisitions

In a press conference on Tuesday, Agriculture Secretary Brooke Rollins said, “There is no doubt that this is a serious threat to our livestock.” But he also disputed claims that the fly is close to or already in the US.

On Monday, state representative Don McLaughlin said on social media that a case of screwworm was found one mile from the Texas border, which Rollins and the USDA denied.

“When that false information gets out, it creates a lot of panic,” Rollins said Tuesday, according to the Texas Tribune. “And they should, especially when it comes from elected officials and the media.”

On Wednesday, Reuters reported that McLaughlin suspected the fly was here. He said samples taken Tuesday from two calves at a farm in La Pryor, Texas – in Zavala County, where it was confirmed that they had screwworm – were being tested for screwworm. Another disease is said to be in the umbilical wound of one of the calves. McLaughlin said he has seen pictures and videos of the animals and that the maggots seen on them look like maggots.

Reuters was shown one of the images, which it reported showed “multiple screwworm-like larvae inside a circular bloody wound on the animal” but said it “could not immediately confirm the image.”

“Right now, it’s not confirmed that it’s a New World screwworm,” McLaughlin told the outlet on Wednesday. “It looks like it is, but it’s not confirmed.”

With the discovery confirmed, the USDA said in a press release Wednesday night that it is establishing a “Joint Incident Command Team” with the Texas Animal Health Commission and sending response personnel to the area. It also establishes a 20-kilometer (12.4 miles) zone around a detected infection for isolation, movement restrictions, and additional surveillance and fly-trapping.

The Screwworm Returns

Screwworms were exterminated in the US in the 1960s during a concerted effort to exterminate their populations. This is done by aerial bombarding of male flies, which is a very effective weapon against these parasites. Mass removal of dud studs removes fertile studs, preventing them from mating with females, which usually mate only once.

With this method, called the Sterile Insect Technique, flies were eradicated not only from the US but from all of Central America. It was announced that they were removed from Panama in 2006.