Screwworm Flies

What is Screwworm?

​Screwworm is a type of fly that can lay its eggs in open wounds, cuts, scrapes, or body openings (like the ears, nose, or belly button) of people and animals. The eggs hatch into tiny worms (larvae/maggots) that burrow into the skin and feed on living tissue. This can cause serious infection if not treated quickly.
Screwworm was eliminated from the United States decades ago, but it has recently been found again in parts of Mexico and Central America. Texas is one of the states most at risk if it spreads northward. Families who live in rural areas and are around livestock are at higher risk.

Who is Most at Risk?

  • Children with uncovered cuts, scrapes, bug bites, or surgical wounds
  • Newborns (the healing belly button/umbilical stump can attract flies)
  • Children who spend a lot of time outdoors around livestock or wildlife
  • Anyone with poor wound hygiene or untreated sores

How to Protect Your Child

  •  Keep all wounds clean and covered
    • Wash any cut, scrape, bug bite, or sore with soap and water right away.
    • Cover wounds with a clean bandage and change it daily or when it gets dirty or wet.
    • Do not let wounds stay open and uncovered, especially outdoors.
  • Protect your newborn's belly button
    • Keep the umbilical cord stump clean and dry.
    • Follow your pediatrician's instructions for cord care.
    • Watch for any redness, swelling, drainage, or unusual smell around the belly button.
  • Be careful around animals
    • Screwworm flies are attracted to wounds on livestock and pets. If your animals have open sores or wounds, get them treated by a veterinarian.
    • Keep children's wounds covered when they are around animals, barns, or pastures.
  • Use insect protection
    • Use age-appropriate insect repellent on your child when spending time outdoors, especially during warm months.
    • Dress children in long sleeves and pants when possible during outdoor activities.
    • Use screens on windows and doors to keep flies out of the home.
  • Practice good hygiene
    • Bathe children regularly, especially after outdoor play.
    • Check your child's skin daily for new cuts, scrapes, or sores — and clean and cover them promptly.

Warning Signs

Take your child to the doctor or emergency room right away if you notice any of the following in or around a wound, cut, or body opening (ear, nose, belly button):

  • A wound that is getting more swollen, red, or painful instead of healing
  • Bad smell coming from a wound or body opening
  • Bleeding or unusual drainage from a wound, ear, or nose
  • Tiny white or tan worms (maggots) visible in or around a wound
  • Your child is unusually fussy, has a fever, or seems sick along with a wound that looks infected

Do not try to remove worms yourself. Bring your child to a healthcare provider so the larvae can be safely and completely removed.

What Your Doctor Will Do

Dr. Kim will send you to wound care if she finds larvae. The wound care doctor will remove all larvae and clean the wound. The wound will need to be rechecked in 48 hours. If there is an infection, your child may be prescribed antibiotics.

We are required to report any confirmed case to public health authorities — this helps protect the whole community.

When to Contact Dr. Kim

  • Any wound that is not healing as expected
  • Any unusual swelling, smell, or drainage from a wound, ear, nose, or belly button
  • If you see any worms or maggots in or near a wound
  • If your child develops a fever along with a wound that looks infected

Prevention for Livestock Owners

Protecting Your Animals

  • Treat animal wounds promptly
    • Inspect all livestock daily for wounds, sores, or signs of fly strike (swelling, bad smell, visible maggots).
    • Clean and treat any animal wounds immediately. Talk to your veterinarian about wound care products and preventive treatments.
    • If you see maggots in an animal wound, collect some in a sealed container with rubbing alcohol and contact your veterinarian and your local USDA APHIS office right away. This is a reportable condition.
  • Time procedures carefully
    • If possible, schedule castrations, dehorning, branding, ear tagging, and other procedures that create wounds during cooler months when fly activity is lower.
    • Treat all procedure wounds with veterinarian-recommended wound care products.
    • Monitor animals closely for 2 weeks after any procedure.
  • Don't forget pets
    • Keep pet wounds clean and covered.
    • See a veterinarian if you notice maggots or non-healing wounds.

Protecting Your Children on the Farm

In addition to the general recommendation tips,
  • Do not let children go barefoot in barns, pastures, or corrals.
  • Wash hands thoroughly with soap and water after handling livestock, before touching children or preparing food.
  • Change clothes and shoes that have been worn in barns or pastures before holding or caring for infants.​

Warning Signs for Your Animals

Report to your veterinarian and local USDA APHIS office immediately if you see:
  • Wounds with maggots that are burrowing into living tissue (not just on the surface)
  • Wounds that are getting larger and deeper instead of healing
  • Strong, foul odor from animal wounds
  • Multiple animals with similar wound problems

Reporting is critical. If screwworm is confirmed, government agencies will respond quickly to stop it from spreading. Early reporting protects your herd, your family, and your community.

USDA APHIS Veterinary Services (Texas): 1-866-536-7593
Texas Animal Health Commission: 1-800-550-8242