New World screwworm (NWS) is inching closer to the U.S. Last week Mexico reported eight new cases in the U.S. neighboring-state of Tamaulipas. A key to slowing down the threat is being proactive.
U.S. Department of Agriculture’s (USDA) import requirements and protocols are one line of defense for NWS and other foreign animal diseases that threaten U.S. livestock. According to USDA, earlier this week, a horse from Argentina was presented for routine importation at an equine import quarantine facility in Florida.
“Upon examination, APHIS identified an open wound with larvae on the animal and promptly collected and shipped samples to the National Veterinary Services Laboratories (NVSL) in Iowa. The horse was immediately treated with medication to kill any larvae in accordance with standard, long-standing import protocols.” the release explains. “This morning, NVSL confirmed that the larvae were NWS larvae. Accordingly, the animal will remain in quarantine until it has been reexamined and determined to be free of NWS.”
This is an example of import protocols working as designed. While this situation does not appear to be associated with the NWS outbreak in Mexico, the release says it underscores the need for vigilance in all of USDA’s coordinated efforts to fight NWS.
New Action To Prevent Northward Spread
Friday, Jan. 30, USDA’s Animal and Plant Health Inspection Service (APHIS) announced a shift in its 100-million-per-week sterile fly dispersal efforts.
“USDA will reallocate aircraft and sterile insects to reinforce coverage along the U.S.-Mexico border,” according to the release. “The new dispersal area, or polygon, will include operations about 50 miles into Texas, along the U.S. border with the state of Tamaulipas, Mexico. Mass production and targeted dispersal of sterile insects are critical components of an effective strategy to fight NWS. Other tools including import protocols and surveillance continue to support these robust efforts to keep NWS out of the U.S.”
Dudley Hoskins, USDA undersecretary of marketing and regulatory programs, says, “At Secretary Rollins’ direction, our highest priority is protecting the United States from screwworm. The northernmost active case of NWS in Mexico is still about 200 miles away from the border, but we’ve seen cases continue to spread in Tamaulipas and further south in Mexico, so we are proactively shifting our polygon as we make every effort to prevent NWS from reaching our border.”
This follows Texas Gov. Greg Abbott’s actions on Thursday issuing a statewide disaster declaration to better equip the Texas NWS Response Team to prevent the potential spread of the NWS fly into Texas and to better protect livestock and wildlife.
“Although the New World screwworm fly is not yet present in Texas or the U.S., its northward spread from Mexico toward the U.S. southern border poses a serious threat to Texas’ livestock industry and wildlife,” said Governor Abbott. “State law authorizes me to act to prevent a threat of infestation that could cause severe damage to Texas property, and I will not wait for such harm to reach our livestock and wildlife. With this statewide disaster declaration, the Texas NWS Response Team can fully utilize all state government prevention and response resources to prevent the re-emergence of this destructive parasite. Texas is prepared to fully eradicate this pest if need be.”
Read more about how to identify NWS:
The Smell You’ll Never Forget: A Calf Infested with New World Screwworm
Protect Your Livestock: Signs of New World Screwworm
Sterile Flies are Key to Stopping NWS
Sterile insect technique, when paired with surveillance, movement restrictions and education and outreach, is an effective tool for controlling and eradicating NWS. Female NWS flies only mate once in their lives, so if they mate with a sterile male, they lay unfertilized eggs that don’t hatch.
Releasing sterile flies just outside of affected areas helps ensure flies traveling to new areas will only encounter sterile mates and will not be able to reproduce.
The updated strategy will include: “USDA will release sterile flies north of the current active NWS cases in Mexico in a proactive effort to create a sterile reproduction buffer zone if the fly moves north from Mexico.”
Because it is important to continue ongoing surveillance efforts while releasing sterile insects, it is possible that sterile NWS flies could be caught and/or reported within Texas. To ensure officials can tell the difference between sterile and wild NWS flies, USDA will dye the sterile pupae, and the dye will transfer to the sterile flies when they hatch. The fluorescent dye will glow under UV light and may also be visible to the naked eye. If a sterile fly is captured in a trap, this dye will allow animal health officials to quickly rule the fly out as a threat.
“USDA will continue to deploy its intensive NWS response efforts including implementing import protocols, ongoing surveillance and trapping efforts along the border, investing in NWS innovation, and supporting robust response activities in Mexico and Central America,” the release says.
Surveillance, Monitoring and Reporting Continues
USDA continues to lead intensive surveillance and monitoring systems along the U.S. border. Teams continue to check 121 NWS-specific traps across high-risk areas of border states and leverage thousands of fruit fly/insect traps aligned all along the Southern border. To date, more than 42,000 flies from traps in all locations have been submitted to APHIS NVSL for identification, with no NWS detections to date.
APHIS Wildlife Services is also leading a coordinated effort to inspect wildlife for signs of NWS infestation. To date, they’ve inspected more than 9,300 wild animals across 39 different species and 131 U.S. counties and found no signs of NWS infestations.
Read more about Wildlife and NWS:
The Importance of Wildlife Monitoring for New World Screwworm
Texas Takes Preemptive Action
The Texas release says Governor Abbott actions against the threat posed by NWS include:
- Directing the Texas Parks and Wildlife Department (TPWD) and the Texas Animal Health Commission (TAHC) to establish a joint Texas NWS Response Team.
- Partnering with the U.S. Department of Agriculture and Secretary Brooke Rollins to create a new $750 million Domestic Sterile NWS Production Facility in Edinburg, Texas.
“I’m glad to see the urgency from the governor’s office matching the seriousness of this threat,” says Texas Ag Commissioner Sid Miller. “The Governor’s disaster declaration gives his task force greater authority, resources, and speed needed to confront the growing threat posed by the New World screwworm. This is a serious risk to our livestock industry and one that the Texas Department of Agriculture has been preparing for through our own heightened surveillance, coordination, and response planning.”
Miller adds, “This fight requires every available resource to be thrown at it without delay, and TDA will continue to work alongside our state and federal partners to protect our livestock, pets, wildlife, and Texas communities.”
For more information on NWS and USDA’s efforts, visit Screwworm.gov
