USDA opens sterile fly plant to fight screwworm as case grow in Texas

• The U.S. and Mexico opened a new facility to produce sterile screwworm flies to combat recent outbreaks.
• The USDA has confirmed 27 total cases of New World screwworm in the U.S., with all active cases currently in Texas.
• The Texas Animal Health Commission has placed parts of 20 counties under quarantine to restrict animal movement.
• Adult screwworms are metallic blue or green flies, and infections are identified by growing wounds with maggots on living animals.

The U.S. Department of Agriculture marked the opening of a sterile fly production plant in southern Mexico to combat the New World screwworm and reported two additional cases in Texas — bringing the U.S. total to 27.

Agriculture Secretary Brooke Rollins was joined by Mexican President Claudia Sheinbaum and other officials on Saturday, June 27, in Metapa, Mexico, to open a 22,000-square-foot facility capable of producing sterile flies to combat the parasitic fly.

"Today represents a major milestone in that fight with the official opening of that facility," Rollins said on social media. "Within 8 weeks, we should have 30 million flies, in 12 weeks - 50 million flies, and by this fall an additional 100 million flies to deploy."

According to the USDA, sterile New World screwworms are released in and around infested areas to increase the likelihood that wild NWS flies will mate with them, while the department continuously monitors new detections and adjusts release patterns to maintain suppression and prevent spread.

It helped eradicate screwworm from the U.S. in 1966 and eliminate a small outbreak in the Florida Keys in 2017.

USDA also reported two new cases over the weekend. One case was confirmed on Friday, June 26, in Jim Hogg County — the county's first reported case. The second confirmed case over the weekend was on Saturday, June 27, in Crockett County — the county's sixth case.

As of Monday morning, June 29, there are 27 cases in the U.S., with Texas the only state reporting active cases.

What does a screwworm fly look like

Adult New World screwworms have orange eyes, a metallic blue or green body and three dark stripes across the back, according to the USDA.

The telltale signs of a screwworm infection are the growing wounds or lesions and the presence of feeding maggots on living animals.

Texas screwworm cases

Here is the breakdown of screwworm case locations in Texas, according to the USDA's screwworm dashboard, and whether they are considered active or inactive.

USDA classifies cases as inactive when the animal has fully recovered or, in cases where treatment was not performed, when appropriate measures have been taken to prevent the spread of the screwworm, such as the proper disposal of the dead, infested animal.

There are currently 26 cases — 21 active and five inactive — in Texas as of the date they were confirmed:

• June 27: One active domestic cattle case in Crockett County.
• June 26: One active domestic cattle case in Jim Hogg County.
• June 24:
  • One active domestic cattle case in Medina County.
  • One active domestic sheep case in Edwards County.
  • Four active domestic sheep cases in Crockett County.
• June 23: Three active domestic cattle cases in Terrell County.
• June 22: One active domestic goat case in Terrell County.
• June 21: Two active domestic cattle cases in Edwards County.
• June 20: One active domestic sheep case in Crockett County.
• June 12: One inactive domestic sheep case in Sutton County.
• June 11:
  • Two active domestic goat and cattle cases in Edwards County.
  • One active domestic cattle case in Tom Green County.
  • One inactive domestic cattle case in Zavala County.
• June 9: One active domestic cattle case in Edwards County.
• June 8:
  • One inactive domestic goat case in Gillespie County.
  • One active domestic cattle case in La Salle County.
• June 7: One inactive domestic cattle case in La Salle County.
• June 5: One active domestic cattle case in Zavala County.
• June 3: One inactive domestic cattle case in Zavala County.

The 27th case in the U.S. was confirmed in New Mexico earlier in the month, but it has now been classified as inactive by the USDA.

Texas Animal Health Commission quarantine zones

The Texas Animal Health Commission has placed parts of 20 counties across West, South and Central Texas under quarantine, restricting animal movement to stop the spread of recently reported cases.

Here's a look at which counties are under quarantine and when the quarantine became effective.

• Zone 1 (effective June 3) — Uvalde and Zavala counties.
• Zone 2 (effective June 7) — La Salle and Webb counties.
• Zone 3 (effective June 9) — Gillespie, Kerr and Kimble counties.
• Zone 4 (effective June 10) — Edwards, Sutton and Val Verde counties.
• Zone 5 (effective June 12) — Tom Green and Coke counties.
• Zone 6 (effective June 13) — Kimble, Schleicher and Sutton counties.
• Zone 7 (effective June 20) — Crockett, Schleicher, Val Verde and Sutton counties.
• Zone 8 (effective June 22) — Terrell and Pecos counties.
• Zone 9 (effective June 24) — Bandera, Medina and Uvalde counties.
• Zone 10 (effective June 26) — Jim Hogg, Starr and Zapata counties.

According to the orders placing the counties under quarantine, the quarantine will remain in effect until the commission lifts it.

Texas screwworm map

Mateo Rosiles is the Texas Connect reporter for USA TODAY and its regional papers in Texas. Got a news tip for him? Email him at [email protected].