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Texas ranchers and those in the cattle industry are on high alert as more cases of New World screwworm infestations are reported close to the Texas-Mexico border.

The parasitic blowflies attack and kill livestock, horses, dogs, cats and even humans. The Head of the Department of Entomology at Texas A&M University, Prof. Phillip Kaufman, said the New World screwworm is different than a regular blowfly.

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"The female fly is laying their eggs only on living animals, and their offspring then eat living animal tissues," said Kaufman. "People think of it as, the animals are being eaten alive, and they really are."

Kaufman said animals can die in five to six days from an infection.

Eleven cases have been reported about 200 miles from the Texas-Mexico border since the end of December. It can spread to other areas when infected animals are transported.

The New World screwworm was prevalent in the U.S. in the 1950s and 60s. If it’s detected in the United States, travel restrictions will likely be put in place to contain it.

Kaufman said ranchers should closely monitor their livestock for symptoms.

"If it’s cattle or sheep, they will go off – it’s called going off their feed – where they won’t come up to the feed bunk, or they stand by themselves because they're not feeling well," said Kaufman. "But if it’s up on the head, the animal may be shaking its head, scratching at its head quite a bit. It’s a painful wound."

He said ranchers should have an established relationship with a local veterinarian and report any suspicious wounds or infestations immediately.

Kaufman said treatment for the animal includes cleaning the wound and applying disinfectant and insecticide. Sterile male flies are then air-dropped in the infected area to prevent spreading.

"Sterile male flies will mate with the wild female flies and essentially trick that fly into thinking that it’s laying viable eggs," said Kaufman, "when in fact it’s laying unfertilized eggs."

Previous screwworm outbreaks have been effectively contained using this strategy.