Updated October 7, 2026

New World screwworm cases have made animal health monitoring an important topic for Texans. For ranchers, horse owners, and families with pets, understanding the reports starts with knowing what a confirmed case means—and what signs require immediate attention.

What Is the Latest Texas Update?

USDA’s current-status page lists an October 6 update announcing a modification to Texas New World screwworm Infested Zone 15. Portions of the zone met the requirements for release, removing screwworm-related animal movement requirements in those areas.

However, several infested zones remain in Texas. Animal owners should check the Texas Animal Health Commission’s current zone map before transporting livestock or pets. Other interstate and international movement requirements still apply.

Active Cases and Past Cases Are Different

When you see a screwworm case count, check whether it refers to active cases or all confirmed cases.

USDA defines an active animal case as one requiring ongoing treatment and disease-control measures. An inactive case means those measures are no longer needed for that individual animal.

Inactive does not necessarily mean the animal survived. It can also mean appropriate measures were completed following an animal’s death.

An animal case becoming inactive also does not automatically release the surrounding area from restrictions. Infested zones have separate requirements for release.

Why Screwworm Is Dangerous

New World screwworm is the larval stage of a fly. Its maggots feed on living tissue, enlarging and deepening wounds as they develop.

The pest can affect livestock, horses, pets, and wildlife. Human infestations can occur, although they are rare.

Warning signs include:

• Maggots inside a wound.

• A strong smell of decay.

• Irritated behavior or repeated head shaking.

• A wound that becomes larger or deeper.

An animal with suspicious wound activity needs prompt veterinary evaluation. Treatment should follow a veterinarian’s recommendations.

What Animal Owners Can Do

Inspect animals regularly and give wounds prompt attention. Check livestock pens and equipment for sharp edges that could cause injuries, and discuss wound care and parasite prevention with your veterinarian.

In infested areas, USDA advises postponing or avoiding procedures that create wounds, such as branding, dehorning, and castration.

For suspected cases in Texas livestock, contact your veterinarian and the Texas Animal Health Commission at 1-800-550-8242. Suspected wildlife cases should be reported to Texas Parks and Wildlife.

Stay Informed as Reports Change

Case totals and zone boundaries can change. Use the USDA screwworm status page to find the official detection dashboard and Texas zone map.

At Best Pest Podcast, host Robert Kerbow discusses pest issues, field experience, and practical information that helps people understand the headlines.

Visit BestPestPodcast.com for more pest education and podcast updates.