This article was originally published at 9:44 a.m. CDT on Monday, June 8. It was last updated with additional information at 12:45 p.m. CDT on Monday, June 8.

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OMAHA (DTN) -- New World screwworm (NWS) is spreading to multiple Texas counties as USDA reported two more confirmed cases on Monday, including a dog infected roughly 500 miles north of where last week's cases were reported.

The Animal and Plant Health Inspection Service (APHIS) confirmed Monday that a calf had been infected in La Salle County, Texas, which is in the adjacent county to where last week's cases were reported.

APHIS also reported a dog was infected from Lea County, New Mexico. APHIS initially reported the infected dog was from Andrews County, which is in the Texas Panhandle. Lea County is adjacent to Andrews County. APHIS stated the veterinarian who submitted samples for the labs was located in Andrews County.

APHIS officials also said they believe the dog was an isolated case, but "the dog's recent travel and exposure remain unknown." USDA had initially stated Monday the dog had traveled recently to Mexico.

"This situation is evolving, and we expect new information to emerge as our investigation continues. USDA is committed to sharing what we learn quickly, accurately, and transparently so animal owners and local communities have the information they need to stay vigilant," said Dudley Hoskins, under secretary for marketing and regulatory programs. "We are working closely with our partners in New Mexico, Texas, and across the region to ensure we identify, contain, and respond to any potential cases as swiftly as possible."

The potential case of a dog traveling from Texas to Mexico and back will raise more questions about USDA's surveillance of the screwworm and protocols for animals crossing the borders between the countries.

Last week, USDA confirmed two cases of calves in Zavala County, both calves and both roughly 6 miles apart and about 60 miles from the Mexico border.

After the second case was reported, the Canadian government issued a temporary ban on livestock imports from Texas. The restriction applies to animals originating from Texas within 21 days before trying to enter Canada.

Montana also has placed restrictions on animals coming from "infested areas" where NWS has been detected. Florida had earlier issued restrictions on livestock from Texas back in April.

On Friday, Texas Gov. Greg Abbott issued an updated statewide disaster declaration for the NWS infestation. Abbott called on the state to use "all available resources of state government to respond to the disaster." Abbott also pressed to speed up the shipment of sterile flies into Texas and to speed up the construction of a new sterile fly facility as well.

"We need a high volume of sterile flies as quickly as possible. It's great news we are getting the volume that we are getting both from Panama, as well as Mexico, but listen, it's critical that the new facility that is being constructed right now be completed even faster," Abbott said, according to the Texas Tribune.

Outgoing Texas Ag Commissioner Sid Miller has been critical of USDA's work on NWS. On Monday, he spoke on the conservative network NewsNation and said Texas officials will need to be more aggressive in dealing with cases.

"We're going to quit waiting on USDA. We're going get this thing under control -- we'll just have to do it ourselves," Miller said to the network.

On Monday afternoon, Agriculture Secretary Brooke Rollins is expected to attend briefings on the screwworm at the new Knipling-Bushland U.S. Livestock Insects Research Laboratory in Kerrville, Texas. She will then hold an update on NWS.

The APHIS Strike Team is at the Texas site and has deployed mobile response trailers, and sterile fly releases are underway with 2 million aerially and 4 million released on the ground per week.

When cases are found, USDA sets up a 20-kilometer zone to prevent the movement of animals from the area without inspection.

NWS is a serious pest that threatens livestock, pets, wildlife, and, in rare cases, people. The larvae burrow into the living tissue of animals, causing severe wounds, animal suffering and significant economic losses.

Officials also have stressed that NWS is not a food safety issue, but rather an animal production challenge. Officials have emphasized the importance of all animal owners to look at their animals on a regular daily basis and report suspected cases to a veterinarian and the Texas Animal Health Commission.

See, "Abbott Declares Disaster as NWS Spreads," https://www.dtnpf.com/…

Also see, "Texas Ranchers Brace as New World Screwworm Returns to US Soil After 6 Decades," https://www.dtnpf.com/…

Chris Clayton can be reached at Chris.Clayton@dtn.com

Follow him on social platform X @ChrisClaytonDTN

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