📌 KWIK SUMMARY
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Quick Fact |
Details |
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What is it? |
A parasitic wound infection caused by larvae of the New World screwworm fly (Cochliomyia hominivorax) that feed on living tissue. |
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Type of condition |
Myiasis infection |
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Common hosts |
Dogs, cats, livestock, wildlife, captive wild and exotic animals, and occasionally birds. |
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Diagnosis |
Veterinary examination (larvae are difficult to visually distinguish from other myiasis flies) |
A new world screwworm infection is one of the most serious parasitic wound infections that pet owners should learn to recognize. Caused by the larvae of the New World screwworm fly, Cochliomyia hominivorax, this condition develops when fly larvae burrow into the flesh of warm-blooded animals and feed on healthy living tissue.
Dogs and cats can also be affected if flies gain access to open wounds, although livestock remain the primary species affected during outbreaks. Early recognition paired with prompt veterinary care dramatically improves outcomes and can prevent severe consequences.
Veterinary Disclaimer : This article is for informational purposes only and does not constitute veterinary advice. Always consult a licensed veterinarian for diagnosis and treatment of any wound, parasite, or health condition affecting your animal.
What Is a New World Screwworm Infection?
At its simplest, a new world screwworm infection is a form of myiasis infection - an infestation of a living animal by fly larvae (maggots).
What sets the New World screwworm apart from many other flies is its behavior: female flies lay eggs in and on open wounds and mucous membranes of warm-blooded animals. After the eggs hatch within a few hours, the larvae burrow deeply into the skin and even into body openings - the eyes, nose, mouth, and genital areas feeding on healthy living tissue rather than dead flesh.
This feeding pattern is what makes the condition so dangerous. Even a tiny scratch, insect bite, tick bite, or recent surgical site can attract egg-laying females. Once established, the larvae can cause severe lesions, loss of function in the affected area, and even death if left untreated.
What do they look like?
The adult screwworm fly is about the size of a common housefly, with distinctive orange eyes, a metallic blue-green body, and three dark stripes running along its back.
How do screwworm larvae infect pets?
Female flies are drawn to the scent of any open wound or mucous membrane. They deposit eggs at the wound edge, eggs hatch in a few hours, and larvae immediately begin burrowing into living tissue as soon as they emerge. If the wound is left untreated, it can be reinfested by additional flies or other myiasis-causing species, compounding the damage.
Which Animals Are at Risk for New World Screwworms?
Pets with recent wounds, skin irritation, surgical sites, tick bites, or existing ear problems face a higher risk of this parasitic wound infection.
Livestock screwworm infection cases occur in cattle, horses, sheep, goats, pigs, and a wide range of wildlife species, including zoo and circus animals. Dogs and cats are also affected.
Screwworm Infection Symptoms Pet Owners Should Watch For
Knowing the screwworm infection symptoms to watch for can make the difference between a quick recovery and a life-threatening emergency.
Pet owners should look for:
- A visible wound that suddenly grows larger or deeper.
- A foul smell coming from the wound.
- Bloody discharge or pus.
- Pain, sensitivity, or obvious distress when the area is touched.
- Constant scratching, licking, head shaking, or restlessness.
- Loss of appetite.
- Visible screwworm eggs or larvae in or around the wound.
- Swelling and irritation around the affected area.
- Loss of function in the affected body part.
KWIK TIP : Wounds involving the eyes, nose, mouth, or genital area should always be treated as urgent, because larvae can burrow into these body cavities and cause severe, sometimes fatal, damage.
How This Parasitic Wound Infection Is Diagnosed and Treated?
This parasitic wound infection requires professional veterinary care. Pet owners should never try DIY removal at home; attempting to remove screwworm larvae. Without proper tools and training, larvae are left behind, worsen tissue damage, or delay urgently needed care.
A veterinarian will examine the wound, safely remove the larvae, clean the wound thoroughly, and prescribe appropriate medication for pain control, infection, and healing. Severe cases may require repeated wound management and ongoing follow-up visits.
Products such as F10 Antiseptic Wound Spray with Insecticide (benzalkonium chloride, polyhexanide, and cypermethrin topical solution), recently authorized by the U.S. FDA under an Emergency Use Authorization, may be used under veterinary guidance for the prevention and treatment of NWS myiasis in certain animals.
Important : F10 Antiseptic Wound Spray with Insecticide is not authorized for use in domestic dogs or cats under the FDA Emergency Use Authorization. The FDA has separately authorized other treatment options specifically for dogs and cats, so pet owners should consult their veterinarian to determine the right one for their pet.
Screwworm Prevention and Control at Home
- Clean and protect any wound right away. Cover it where possible, and recheck it daily.
- Treat tick problems promptly. Tick bites are common entry points for infestation.
- Keep injured or postsurgical pets indoors whenever you can.
- Pay special attention to wounds around the eyes, nose, mouth, and genital area - these are high-risk locations.
- Schedule prompt veterinary care for any wound that looks unusual, smells bad, fails to heal, or suddenly gets worse.
Conclusion
A new world screwworm infection is a serious parasitic wound infection, but it is both preventable and highly treatable when caught early. Recognizing screwworm infection symptoms quickly is the single most important step a pet owner can take. Regular daily wound checks and prompt veterinary care remain the best defense for keeping your pets safe, healthy, and protected.
