Parasite Control

Emergency Use of Animal Drugs Approved to Combat New World Screwworm

Tue, 19 Aug 2025 16:09:22 GMT

The U.S. Department of Health and Human Services (HHS) issued a declaration on Aug. 19 allowing the U.S. Food and Drug Administration (FDA) to issue Emergency Use Authorizations (EUAs) for animal drugs to treat or prevent infestations caused by the New World screwworm (NWS).

This declaration applies only to drugs for animals. NWS infests warm-blooded animals, including livestock, pets, wildlife, and, in rare cases, humans, causing severe tissue damage and sometimes death. The risk to human health in the U.S. remains very low, but the potential future threat to animal populations and the food supply chain requires proactive action.

Although eradicated from North America and Central America decades ago, NWS has progressed north since 2022 and is now approaching the U.S. border with Mexico. This parasite poses an emerging threat to livestock and food security, with potential impacts on both national security and animal health.

“Today we are taking decisive action to safeguard the nation’s food supply from this emerging threat,” says HHS Secretary Robert F. Kennedy, Jr. “This authorization equips FDA to act quickly, limit the spread of New World Screwworm, and protect America’s livestock.”

Currently, there are no FDA-approved drugs for NWS in the U.S. The FDA through an EUA can authorize the flexible, faster use of certain animal drug products that may be approved for other purposes, or available in other countries, but not formally approved for NWS in the U.S. This ensures veterinarians, farmers, and animal health officials have timely access to the tools they need to protect pets, livestock and the nation’s food supply.

“Thank you to my friends and partners Secretary Kennedy and Commissioner Makary who are answering the call and supporting our aggressive plan to push back and ultimately defeat this devastating pest. This emergency use authorization is another tool we can use in the fight against New World Screwworm,” says Secretary of Agriculture Brooke L. Rollins. “Our cattle ranchers and livestock producers are relying on the Trump Administration to defend their livelihoods. Stopping this pest is a national security priority and we are linking arms across President Trump’s cabinet to defend our borders and push back this threat.”

FDA Commissioner Marty Makary, M.D., M.P.H., adds, “Our priority is to safeguard both animal health and the nation’s food supply. FDA is acting swiftly and responsibly to help ensure we have the necessary tools to prevent and control New World Screwworm, minimizing risks to agriculture and public health.”

FDA will provide future guidance to veterinarians and stakeholders on the appropriate use of any products authorized for emergency use and update the New World Screwworm: Information for Veterinarians page.

Mexico Takes Additional Measures to Help Fight New World Screwworm

Thu, 01 May 2025 18:24:33 GMT

USDA has announced that Mexico agreed to additional measures to help fight New World Screwworm (NWS). The U.S. had given Mexico a deadline of April 30 to follow protocols in place or the U.S. would put restrictions on cattle imports.

USDA Secretary Rollins posted on X.com that Mexico has resumed efforts to help fight NWS with the following:

Eliminate restrictions on USDA aircraft
Waive customs duties on eradication equipment
Increase surveillance

(X.com)

Rollins says ports will remain open to livestock imports at this time, however if at any time these terms are not upheld, port closure will be revisited. The secretary had sent a letter to Mexico outlining the expectations for cooperation on the issue.

Protocols had been established in February after the pest was discovered in southern Mexico in November 2024.

“I am happy to share Mexico has continued to partner in emergency efforts to eradicate the New World Screwworm,” Rollins says. “This pest is a devastating threat to both of our economies, and I am pleased to work together with Mexico in good faith to protect the livelihoods of our ranchers and producers who would have been hurt by this pest.”

Rollins reiterated that USDA is working every day to keep pests and disease from harming the agricultural industry.

“I thank our frontline USDA staff and their counterparts in Mexico for their work to ensure the screwworm does not harm our livestock industry,” she adds.

NWS is a deadly parasitic fly that infests warm-blooded animals, causing severe wounds and complications that can lead to death.

Your next read: Streamline Spring Cattle Processing with These 3 Stress-Reducing Steps

Cattle and Bison Imports from Mexico to Resume Under New Protocols

Mon, 03 Feb 2025 14:46:37 GMT

On Feb. 1, the United States Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) announced cattle and bison imports from Mexico will resume utilizing new preventative measures. Imports are scheduled to begin in the next several days.

In November 2024, APHIS halted shipments of Mexican cattle and bison after a positive detection of New World screwworm (NWS) in southern Mexico.

According to the release, APHIS and Mexico agreed to and implemented a comprehensive pre-clearance inspection and treatment protocol to ensure safe movement and mitigate the threat of NWS. APHIS says its top priority is to protect American livestock from foreign pests.

Newly released preventative measures include:

Mexico identified and prepared pre-export inspection pens in San Jeronimo, Chihuahua, and Agua Prieta, Sonora, which APHIS visited, inspected, and approved.
Cattle and bison will be inspected and treated for screwworm by trained and authorized veterinarians prior to entering the pre-export inspection pens, followed by inspection by Mexican officials before proceeding to final APHIS inspection before crossing at the Santa Teresa and Douglas Ports of Entry, respectively.
Cattle and bison approved for importation will also be dipped in a solution to ensure they are otherwise insect- and tick -free.

The United States and Mexico are working closely to approve additional pre-export inspection pens and reopen trade through other ports of entry, the release says.

APHIS will continue working with partners in Mexico and Central America to eradicate NWS from the affected areas and to reestablish the biological barrier in Panama, which has been maintained since 2006.

In the last two years, screwworm has spread north of the barrier throughout Panama and into Costa Rica, Nicaragua, Honduras, Guatemala, El Salvador, Belize and now Mexico.

The APHIS release says the increase is due to multiple factors including new areas of farming in previous barrier regions for fly control and increased cattle movements into the region.

APHIS is releasing sterile flies through aerial and ground release at strategic locations, focusing on Southern Mexico and other areas throughout Central America.

A complete list of regions APHIS recognizes as affected by screwworm as well as more detailed information on trade restrictions can be found on the USDA APHIS Animal Health Status of Regions website .

Texas Tech Veterinarian Weighs In On New World Screwworm

Fri, 06 Dec 2024 13:26:40 GMT

USDA’s Animal and Plant Health Inspection Service (APHIS) has heightened import restrictions on animal products from Mexico since detection of New World Screwworm in a Mexican cow on Nov. 22. It has also intensified efforts in Central America to contain the spread of New World screwworm. Animal health experts say it’s warranted as it’s a significant threat to U.S. animal health.

“It can have a huge impact, certainly an economic impact, because it decreases the health and wellness of our livestock,” says Jennifer Koziol, associate professor of food animal medicine and surgery, Texas Tech School of Veterinary Medicine. “We’re thinking about loss of animal use, and certainly thinking about our wildlife populations that could be decimated by this disease.”

The pest can infest any warm-blooded animal, including humans.

“The screwworm fly lies its eggs in an open wound on the animal,” Koziol says. “These larvae or worms just eat the flesh of that animal. It can be devastating to any animal that becomes infected with screwworm.”

Koziol advises producers to monitor herds, especially in the southern U.S., and use preventative measures, including sterile fly introduction or animal health products.

“It looks like Doramectin has about a 28-day efficacy period against this,” she adds. “Ivermectin is similar. We’re looking at those products and how we can use them as an aid in preventing disease.”

According to APHIS, it appears this case is isolated, which leaves the cattle industry asking when will the border restrictions ease for Mexican cattle and product imports.

Koziol says the border could likely open after Christmas or around the first of January.

“We’re working really hard to set up some pre-export pens that APHIS will go in and OK and feeling very good about the protocols set in place,” she adds.

Impact on Cattle Prices
Market analysts say when the border reopens it might hurt cattle prices in the South more than the North.

“They could break a little bit, but I think the reality of the deal is it looks like there’s enough people out there who believe that ownership is the key when it comes to having some cattle around them as tight supplies are very, very tight of yearling-type steers,” says Brad Kooima, Kooima Kooima Varilek. “That’s going to still put a prop underneath the thing because the cash index is so strong.”

The price impact will likely be short lived.

Read more: New World Screwworm: Latest Update from USDA-APHIS

APHIS Increases Import Restrictions on Animal Products from Mexico on Confirmed Case of New World Screwworm

3 Universities Join CDC Midwest Center’s Effort Against Disease-Bearing Ticks and Mosquitoes

Thu, 01 Sep 2022 19:36:30 GMT

Purdue University, Indiana University and the University of Notre Dame have joined the Midwest Center of Excellence for Vector-Borne Diseases. The $10-million Midwest center, led by the University of Wisconsin-Madison, is funded for five years by the Centers for Disease Control and Prevention.

“The new Indiana partners are fortifying the center’s capacity to advance innovative vector-control approaches for mosquito and tick threats that are unique to the Midwestern environment,” said Lyric Bartholomay, professor of pathobiological sciences at University of Wisconsin-Madison and co-director of the Midwest Center of Excellence for Vector-Borne Diseases. “Connections to these three outstanding universities provide the exciting potential to train Hoosiers to join the battle against vector-borne diseases.”

The first round of funding for the center in 2017 established a collaboration between universities and public health agencies in Wisconsin, Illinois, Iowa, Michigan and Minnesota. Together they work to better control mosquitoes and ticks —vectors that spread pathogens.

The academic partners, which will work closely with the Indiana Department of Health, all have industry connections and expertise in vector-control product development. This includes designing, testing and evaluating new insecticides, sprays and devices to control mosquitoes and ticks.

“We’re grateful and excited to be included in this second round,” said Catherine Hill, professor and interim head of Purdue’s Department of Entomology in the College of Agriculture. “Unfortunately, mosquitoes and ticks don’t pay any attention to state borders.”

All three universities will conduct a series of user-acceptance studies for products designed to control ticks and mosquitoes.

“Having buy-in from the stakeholders, particularly for vector control, is critical,” said Molly Duman Scheel, the Navari Family Professor of Medical and Molecular Genetics at the IU School of Medicine-South Bend. “When they feel like they’re part of the technology development process, people embrace it. And if they embrace it, they have more tendency to use it.”

The project also will provide opportunities for early career scientists. A key goal is to produce the next generation of vector biologists by training students and giving early career scientists new professional opportunities.

“Because Indiana is now part of the center, the educational piece is going to be big,” said John Grieco, research professor of biological sciences at Notre Dame. “We’re now included in all discussions around the various vector-related issues in our state. It pulls everybody together as a cohesive unit.”

Hill’s Purdue team is pursuing minimum-risk plant-derived products for controlling Lyme disease and tick pests.

“Ticks are a big problem,” Hill said. “And one tick, in particular — Ixodes scapularis, the Lyme disease tick — is a vector of Lyme disease and multiple other diseases in the region.”

The lone star tick (Amblyomma americanum) and the dog tick (Dermacentor variabilis) also pose problems for Indiana. And as climate change continues, they pose a potential invasive problem for regions north of Indiana, as well.

“The emphasis is going to be on the Lyme disease tick because that’s public enemy No. 1 in North America,” Hill said.

But the Asian longhorned tick may someday pose a threat. An invasive species first detected in the United States in 2017, it has now become established here. The tick is found in 17 states, including Kentucky, on Indiana’s southern border. If it moves north, it could become a vector of various human-disease pathogens. But the tick also threatens livestock and other animals.

In her Purdue Extension role, Hill receives many queries about how people can control ticks on their properties without using highly toxic, synthetic insecticides. Purdue’s goal of a plant-based product would help. There are permethrin-based or pyrethroid-based neurotoxins available that are reasonably safe for humans, Hill said, “but I don’t like the thought of putting that in the environment.”

Scheel’s lab will target Culex mosquitoes, carriers of the West Nile virus.

“West Nile virus is one of the big impacts on Hoosiers in terms of mosquito-borne illnesses in the United States,” said Scheel, who is also an adjunct associate professor of biological sciences at Notre Dame. The virus affects Chicago, too, where her lab will join the center’s ongoing field tests for Culex larvae control.

Scheel’s lab is modifying yeast to include an environmentally safe, RNA-based pesticide that can be fed to mosquitoes. The yeast is dead when fed to the larvae, which prevents releasing the live microorganisms into the environment. Researchers widely use RNA technology to study gene function. Scheel aims to move the technology from the lab to the field.

“The RNA is directed specifically against mosquito genes and not humans or other insects,” she explained. “Some pesticides used broadly across the world are not environmentally friendly or specific to mosquitoes.”

In recent years, Scheel’s team has conducted extensive public engagement studies on Trinidad in the Caribbean with funding from the U.S. Agency for International Development and the Department of Defense. Her team will begin doing public outreach in the United States, too, with the CDC grant support.

“When we do this stakeholder engagement, we also teach a lot of people about mosquitoes. That’ll be an immediate impact,” Scheel said.

The lab that Grieco runs with Nicole Achee, research professor of biological sciences at Notre Dame, is developing spatial repellants. Unlike topical repellants for the skin, spatial repellents include hanging strips or tabletop devices that create a mosquito-free environment within a certain area.

“We’re trying to focus more on the natural products — botanicals, geranium oils and other extracts — because those are going to be much more accepted by the U.S. market,” Grieco said.

Grieco and Achee have tested mosquito control methods to reduce malaria and dengue in Africa, Asia and Central and South America. Their work has included knowledge, attitudes and practices evaluations of their products among local residents. They envision students in Notre Dame’s Master of Science in Global Health program to undertake such evaluations as capstone projects.

The Notre Dame researchers recently began conducting trials of improved practices (TIPS) to make product improvements. Now they will begin adding lessons learned from the TIPS studies into their U.S. evaluations.

Once a final product is developed, it must then pass through many U.S. and global regulatory agencies to ensure that it meets environmental safety requirements.

Read More:

JEV in Australia: A Warning Shot that the U.S. Could Be Next?

Asian Longhorned Ticks and Theileria: What you need to know

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