Does the New World Screwworm Affect Cat Fanciers in the United States?

September 30, 2026

YES!

The question is not whether it affects you, but how and why.

 Kelly Crouch
CFA Legislative Information Liaison

 

As of September 2026, 45 states have implemented travel regulations for all warm-blooded animals to prevent the spread of New World Screwworm (NWS). This includes cats and affects exhibitors, breeders, and show events!

The NWS larvae endanger the animals they infest and have spread to the U.S., traveling “on the backs” of their hosts. Cattle and wildlife are the parasite’s most common intermediate hosts. But cats, dogs, birds, and humans can also become infested. The NWS fly lays eggs in the host’s wounds and mucous membranes. But unlike most fly maggots, screwworm larvae eat living flesh. This can enlarge wounds, allow opportunistic bacterial infections, and even kill the host. Wounds as small as a tick bite give flies opportunities to lay eggs (Hanna and Bynum).

Imagine what a widespread infestation could do to ranches, farms, pets, and animal businesses. In 1957, the NWS infested Florida before spreading across the country. It was finally eradicated in 1966, but the infestation cost animal industries dearly. Damages ran $50-$100 million each year in the Southwest alone (University). The 2026 value of $100 million in 1957 is almost $1.2 billion according to the “In 2013 Dollars” consumer price index calculator. The significant loss of cattle increased beef prices for consumers and impacted dairy production (“New World Screwworm: Historical”). The Federal Reserve Bank of Texas reports that a full-blown outbreak could cost the Southwest cattle industry $ 3 billion (Maruf). No wonder states want to stop the spread. Quarantines and movement restrictions can significantly reduce physical spread because screwworms travel fastest over long distances when infested animals are transported (Anzaldúa).

Travel Impact on Fanciers

Every fancier needs to monitor NWS spread because it affects whether you can travel with your cats (or any other warm-blooded animal), and what requirements you must meet. It could also affect whether clubs can afford to host cat shows. Hopefully, most exhibitors will not be affected beyond that. But if a significant portion of exhibitors choose not to attend a particular show because of travel restrictions, the club may not break even without them. Clubs may also have to consider alternate locations for their regular show hall if it is located near an infested or regulated area. Almost all U.S. states have implemented NWS rules in addition to their regular animal entry requirements. Fanciers need to know both. One Texas fancier traveling to a Missouri show reported that meeting regulations for Missouri and every state traveled through cost them $150 per cat. That cost will vary by state and your travel plans.

People traveling with pets through and to multiple states must meet each state’s requirements for both outgoing and return trips. Unfortunately, the requirements change from state to state. How they define regulated regions (this term is used herein because states use different definitions and classifications of what is regulated) and the requirements for each type of regulated region vary widely. One state includes any state bordering a state with an infestation; another includes any U.S. region within 125 miles of an infested area in Mexico. Another state includes quarantine requirements. Some states require preventative treatments for entry. If a regulated area is on your itinerary, the requirements will likely increase for the remainder of your trip. Common carriers may also implement their own rules. Requirements may change in reaction to changes in the NWS infestation situation.

What Fanciers Should Do When Traveling:

  1. Monitor the infestation situation. The APHIS NWS Dashboard can help monitor where the NWS has been detected. https://www.aphis.usda.gov/animals/animal-health/livestock-and-poultry-disease/stop-screwworm/current-status/confirmed
  2. If planning a trip or shipping an animal, check the applicable state and common carrier rules. Links to state and federal government sites on traveling with animals during the NWS situation can be found on the CFA Legislative Group Blog at https://legislative.cfa.org/new-world-screwworm-restrictions-on-travel/ Plan your trips around regulated areas if you can.
  3. Meet the requirements for every state you travel to or through on your outgoing or return trips. This includes the state’s normal entry requirements as well as the emergency NWS requirements. Only USDA-accredited vets can provide Certificates of Veterinary Inspection (CVI). Accredited veterinarians in your county can be found at https://vsapps.aphis.usda.gov/vsps/public/VetSearch.do. Call your preferred vet first, as not all veterinarians choose to be listed. Keep copies of your documentation with you wherever you have your cats.
  4. Check the state entry requirements often. The NWS infestation is fluid, and requirements may change.
  5. There may be additional requirements for animals imported into the country or exported to other countries.
  6. If your trip will last longer than the effective dates of the CVI (and other requirements), you must plan to go through the process as often as necessary to complete your trip.

While NWS travel restrictions are extremely inconvenient for exhibitors and clubs, rescues in regulated areas are bearing the brunt of NWS, facing increased euthanasia rates as Texas rescues depend heavily on sending shelter animals north to find new homes. The restrictions remove this option for shelters and rescues, causing shelters to be overrun with animals (Adoptions). Fanciers involved in rescue have likely noticed this issue.

New World Screwworm Life Cycle

The adult fly is not a great risk, except that it lays eggs on the host animals that hatch into hungry, live tissue-eating larvae. An adult fly will generally travel less than ten miles to find appropriate hosts for the up to 3,000 eggs it will lay. But in arid areas with fewer potential hosts, it may travel as far as 120 miles in its lifetime to seek mates and hosts. Thus, adults contribute little to the rapid long-distance spread of NWS. Instead, the host animal’s movement drives rapid, long-distance travel. That means the fastest spread occurs in the egg and larval stages.

The eggs hatch into larvae within 12 to 24 hours. For the next five to seven days, the larvae feast on the host’s living tissue as it prepares for the next stage. Then the larvae drop off the animal to pupate in the ground for 7 to 54 days, after which the adult fly emerges, and the cycle begins anew (“Digging Deeper”). Minimizing spread requires preventing infested animals from traveling to uninfested areas. The best way to do that is to monitor the situation and restrict movement of potential hosts. Eradication, however, requires a complementary solution.

Eradication

The 1957 NWS infestation was eventually eliminated in 1966 using the Sterilized Insect Technique (SIT). Unfortunately, when NWS hit the U.S. in June 2026, only the Panama plant was still producing irradiated flies. The Panama plant produces about 100 million flies per week for multiple countries. To fight the infestation, it is estimated that 400-500 million sterilized flies must be released per week (Christensen). Despite having two years’ advance notice, the government only recently started building more plants. According to Texas Public Radio, the USDA hopes that, with the new plants being built, production will reach 500 million sterilized flies per week by the summer of 2027 (Staff). SIT is an effective way to deal with NWS. But like TNR for reducing the number of community cats, it is a gradual process. It is hard to say how long it will take to eradicate the fly this time. The 2016-2017 spot infestation in Florida took only five months to eradicate. Hopefully, the eradication of the 2026 infestation will be measured in months rather than years. Minimizing spread will hopefully speed up eradication.

Detection

Cats are not common hosts for NWS infestations, but they are not immune. Neither are dogs, guinea pigs, ferrets, hamsters, birds, or other warm-blooded pets. It is cringeworthy to note that screwworms have been known to infest a cat’s mouth and take up residence in a dog’s eye socket (Verocai). Pet owners in or near infested zones should monitor their animals daily. Any wound, surgical area, umbilical cord, or mucous membrane allows the fly to lay eggs. Remember, even a tick bite invites screwworms.

Look for (Verocai):

  • Visible larvae.
  • Wounds, especially ones that rapidly worsen.
  • Foul odors.
  • Swelling or irritation around a wound.
  • Watch for unusual behavior such as limb shaking, licking wounds, loss of appetite, aggression, or lethargy.

If you suspect an infestation, isolate the animal and call your vet immediately. Treat it as an emergency – early detection of the infestation is critical for effective treatment. Your vet will have to mechanically remove the larvae and send specimens out to determine if it is NWS. Then they will clean and treat the wound. Prescription treatments and preventatives are approved for dogs and cats. Preventatives may have to be given within a specified time period for travel purposes depending on the state. If it is screwworm, state officials must be notified.

Prevention

For fanciers near the southern U.S. border, in infested zones, or who have traveled in Latin America with their pets, there are some things you can do to prevent infestations (Verocai):

  • Monitor your pets for wounds, foul odors, and larvae daily.
  • Treat wounds immediately (unless you suspect larvae; then call your vet immediately and isolate the animal. Keep them clean with a treatment that deters NWS flies, if possible.
  • Avoid activities that could result in wounds, especially for animals that go outside.
  • Discuss preventatives with your veterinarian.
  • During a local outbreak, keep your animals inside as much as possible to reduce exposure to the fly.

Resources

For more information on NWS, check out the following links:

CFA Legislative Group Blog, NWS page: https://legislative.cfa.org/

USDA Screwworm page: Screwworm.gov

USDA NWS FAQ: https://www.aphis.usda.gov/sites/default/files/nws-myth-busters.pdf

VIN News: https://news.vin.com/default.aspx?pid=210&Id=13359826&f5=1

Texas A&M pet protection: https://vetmed.tamu.edu/news/pet-talk/https-vetmed-tamu-edu-news-pet-talk-new-world-screwworm-pet-protection-prevention/

Texas A&M animal care: https://agrilifeextension.tamu.edu/companion-animal-care-nws/

AVMA: https://www.avma.org/resources-tools/one-health/veterinarians-and-public-health/new-world-screwworm

Texas Tribune, the eradication game plan: https://www.texastribune.org/2026/06/24/new-world-screwworm-texas-sterile-flies-usda-trump-brooke-rollins/

USDA Accredited Veterinarians: https://vsapps.aphis.usda.gov/vsps/public/VetSearch.do

Conclusion

Fanciers and pet owners will have to navigate the NWS travel rules for the foreseeable future. With no end date in sight, stress increases for animal owners, businesses, and states alike. But not eradicating NWS will lead to a far worse situation for everyone. The good news is there is every reason to think NWS will be eradicated again in time, and hopefully, sooner rather than later.

Citations

Anzaldúa, Omar, and Juan Puente. “USDA Confirms Three New Screwworm Cases in Texas.” Https://Www.Kgns.Tv, KGNS, 8 June 2026, www.kgns.tv/2026/06/08/usda-confirms-three-new-screwworm-cases-texas/. Accessed 28 Sept. 2026.

Christensen, Jen. “A Billion Flies Are Now in the Screwworm Fight. Will There Be Enough?” CNN, Cable News Network, 7 Sept. 2026, www.cnn.com/2026/09/07/health/screwworm-billion-flies  Accessed 16 Sept. 2026.

Dexter, Jessica. “The Historical Impact of New World Screwworm Outbreaks in U.S.” AG Proud RSS, AG Proud, 22 Apr. 2025, www.agproud.com/articles/61428-the-historical-impact-of-new-world-screwworm-outbreaks-in-us Accessed 16 Sept. 2026.

“Digging Deeper: How to Protect Pets from the New World Screwworm.” Veterinary Medicine & Biomedical Sciences, Texas A&M, 11 May 2026, vetmed.tamu.edu/news/pet-talk/https-vetmed-tamu-edu-news-pet-talk-new-world-screwworm-pet-protection-prevention/. Accessed 16 Sept. 2026.

Hanna, John, and Russ Bynum. “What to Know about the New World Screwworm Fly and Its U.S. Reappearance.” PBS, Public Broadcasting Service, 5 June 2026, www.pbs.org/newshour/nation/what-to-know-about-the-new-world-screwworm-fly-and-its-u-s-reappearance  Accessed 16 Sept. 2026.

Hanna, John. “Texas Pet Adoptions on Hold Due to Screwworm Concerns.” ABC13 Houston, 21 Aug. 2026, abc13.com/story/texas-pet-adoptions-hold-due-concerns-new-world-screwworm/19714370/. Accessed 16 Sept. 2026.

Maruf, Ramishah. “What Screwworm Means for Your Beef Prices | CNN Business.” CNN, Cable News Network, 9 June 2026, www.cnn.com/2026/06/09/business/what-consumers-should-know-about-screwworm  Accessed 16 Sept. 2026.

“New World Screwworm:  Historical Impacts and Current Threats.” Borderlands Research Institute, BRI, 24 Apr. 2026, bri.sulross.edu/new-world-screwworm-historical-impacts-and-current-threats/. Accessed 16 Sept. 2026.

Staff, TPR. “New World Screwworm Cases Climb to 49, with Latest Found in Presidio County Horse.” TPR, Texas Public Radio, 10 Sept. 2026, www.tpr.org/public-health/2026-07-03/31-confirmed-new-world-screwworm-infestations-texas-tracker-and-what-you-need-to-know Accessed 16 Sept. 2026.

University of California – San Diego. “The U.S. Eradicated This Flesh-Eating Parasite. Now It’s Back.” ScienceDaily, 15 Sept. 2026, www.sciencedaily.com/releases/2026/09/260914102439.htm. Accessed 28 Sept. 2026.

Verocai, Guilherme G., et al. “Companion Animal Care in the Face of the New World Screwworm (NWS) Threat.” Texas A&M AgriLife Extension Service, Texas A&M, 2 July 2026, agrilifeextension.tamu.edu/companion-animal-care-nws/. Accessed 16 Sept. 2026.