New World Screwworm Awareness: What Pet Owners Need to Know

We want to keep you informed about New World Screwworm, an emerging animal health concern, and what it means for your pet.

What is New World Screwworm? 

New World Screwworm (NWS) is a parasitic fly whose larvae (maggots) burrow into the living flesh of warm-blooded animals through wounds, causing a painful and potentially fatal infestation called myiasis. Even a small wound can become an entry point, including something as minor as a scratch, a tick bite, or a surgical incision.

NWS affects dogs, cats, and other mammalian pets including ferrets, rabbits, and guinea pigs, as well as livestock and, in rare cases, people. 

While NWS was eradicated from the United States decades ago, it has been moving northward, and the first animal case in the current outbreak was confirmed in Texas on June 3, 2026. 

We know you may have concerns, and we are here to keep you informed and help keep your pet safe. 

What should you watch for? 

Contact us right away if you notice any of the following: 

• Enlarging wounds that do not heal and have a rotten smell, bloody or unusual discharge
• Wounds that appear to be getting deeper rather than better
• Visible larvae (maggots) in or around a wound
• Signs of pain, irritation, or excessive scratching around a wound site 
• Head shaking (especially relevant to ear injuries) 
• Behavioral changes: withdrawal, restlessness, or unusual aggression 
• Loss of appetite or lethargy 
• Isolation from family or other pets 

Even a minor wound can become a site of infestation. Do not wait, contact us immediately if you notice any of these signs. 

How can I protect my pet and myself? 

• Continue your pet's prescribed preventative medication. If your pet is not currently on parasite preventatives, or if their protection has lapsed, contact us to discuss the best options for getting them back on track. 

• Inspect your pet daily from head to tail. Pay close attention to any wounds, sores, or skin irritations, even small ones, and contact us with any concerns. 

• If your pet lives near the southern U.S. border or will be traveling to or from Latin America, call us before the trip. 

Rarely, humans can become infested with screwworm, but direct transmission from animals or other humans does not occur, as it is not contagious. Good hygiene, covering wounds, and prompt wound care are the best protection. For any personal health concerns, please contact your physician. 

We are here for you and your pet. If you notice any concerning wounds or signs of illness, please do not wait, call us right away. 

New World Screwworm Treatment 

Effective treatment options are available. If you have concerns, the most important thing you can do is reach out promptly: earlier treatment makes a significant difference in the outcome. 

This is not a wait-and-see situation. If you see a wound that smells bad, looks like it's getting worse, or has any unusual material in it, call us right away. Please don't wait. 

Frequently Asked Questions 

Is New World Screwworm actually in the U.S. right now?

Yes. The first animal case in the current outbreak was confirmed in Texas on June 3, 2026.

My pet never goes outside. Do I still need to worry?

Strictly indoor pets have a very low risk, but it is not zero, especially if they step outside even briefly. For pets with no outdoor exposure in a lower-risk area, and on regular preventatives, the risk is minimal. Staying alert to any unusual wounds is always a good habit. 

Can it spread to my family?

In rare cases, screwworm can affect people through open wounds with direct contact with the fly. This is not a contagious disease and cannot spread directly from animals to humans. Good hygiene, covering wounds, and prompt wound care are the best protection. For any personal health concerns, please contact your physician. 

What does treatment look like, and what will it cost?

Treatment involves a veterinary exam, thorough wound care, and if warranted, an FDA-authorized oral medication. Cost depends on your pet's specific situation. We are happy to walk you through what to expect — would you like to schedule an appointment? 

My pet is already on a regular preventative such as Credelio/quattro, Simparica/trio, Bravecto, NexGard, or Revolution Plus. Can they still become infested with NWS?

While infestation in a pet regularly receiving one of these preventatives is very low, the risk is not zero. Monitoring for any abnormal wounds or new lesions is still recommended, and prompt evaluation by a veterinarian should there be any concerns. 

Questions? Give us a call. 

Our team is staying current on guidance from USDA APHIS, the FDA, and AVMA, and we're here to answer your questions, assess your pet's risk, and provide personalized recommendations. If your pet is not currently on parasite preventatives, or if their protection has lapsed, contact us to discuss the best options for getting them back on track.