Ranchers across the Rio Grande Valley said they are on high alert after a new case of the parasitic New World screwworm was detected in the town of Sabinas Hidalgo in the Mexican state of Nuevo Leon.

It’s about 70 miles from the Starr County border city of Roma.

Texas leaders said the parasite can cripple the livestock industry, if it makes its way to the Valley.

Congressman Henry Cuellar, who represents Starr County, said the state and federal government have been working to keep the pest out of the Valley.

The parasite attacks warm-blooded animals, including humans. The pest is carried on larvae laid by flies on the wounds of cattle, causing a possible fatal infection that can spread.

Mexico has reported more than 500 active cases in cattle across southern states, triggering the United States to block the imports of live Mexican cattle for a second time over the summer.

There have been no reported cases of the parasite in Texas.

“We're asking the USDA to move faster to work with our Mexican counterpart because here, prevention is the best medicine because once it gets over here it’s going to be a lot more expensive, and it's going to be a lot more of a negative impact to our cattle folks,” Cuellar said.

In June, the U.S. Department of Agriculture announced the creation of a screwworm sterile fly facility in Hidalgo County.