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 in Andrews County, which is in the Texas Panhandle.

"A veterinarian in Andrews County submitted the samples from the infested dog. Details on this case will be shared as they are available, but early reports indicate the dog was recently in Mexico," APHIS stated in a news release.

The 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.

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.

"Over the past week, USDA has identified and expeditiously confronted four confirmed detections of New World screwworm. While we address these instances that require immediate attention, and continue to sample suspected cases, we are simultaneously working to eradicate the pest entirely," said Dudley Hoskins, under secretary for marketing and regulatory programs. "We need the partnership of animal owners across the region -- please stay vigilant, check your animals closely, and report anything that looks suspicious. Together, we can protect our livestock, our communities, and the health of animals nationwide."

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

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