What is the New World screwworm?

The New World screwworm (Cochliomyia hominivorax) is a parasitic fly whose larvae burrow into the living flesh of warm-blooded animals — livestock, wildlife, pets, and rarely humans. The United States eradicated it in the 1960s using the sterile insect technique, so its return to Texas in June 2026 is the first domestic detection in about 60 years.

How many screwworm cases are confirmed in Texas?

As of August 16, 2026, USDA APHIS has confirmed 46 infestations in the United States — 45 in Texas and 1 in New Mexico — across 16 Texas counties. This page is updated as USDA publishes revised totals.

Which Texas counties have confirmed screwworm cases?

USDA reports cases across 16 Texas counties. The counties individually named in reporting are Zavala County, La Salle County, Gillespie County, Edwards County, Tom Green County, Sutton County, Jim Hogg County, Pecos County, Uvalde County, Medina County, Terrell County, Crockett County, Brewster County, Schleicher County, Starr County, Val Verde County, with Crockett County described as the epicenter. The Texas Animal Health Commission has placed portions of these and surrounding counties under an infested-zone quarantine with animal-movement restrictions.

How do I report a suspected screwworm case?

Report suspected infestations to the Texas Animal Health Commission (1-800-550-8242) or your local veterinarian immediately. Look for maggots in a wound that appear to burrow deeper rather than feed at the surface, a foul odor, and wounds that enlarge over time. Early reporting is critical to containment.

Is the screwworm dangerous to humans and pets?

Screwworm primarily affects livestock and wildlife, but it can infest pets and, rarely, humans — any warm-blooded animal with an open wound is at risk. Keep wounds on animals clean and covered, monitor pets after outdoor injury, and seek veterinary or medical care for any wound with maggots that worsens.

Active outbreak — updated August 23, 2026

New World Screwworm in Texas: Case Tracker & Map

A running record of confirmed New World screwworm infestations in Texas — where cases are, how the outbreak has grown, and the official channels for reporting and response. Distilled from USDA APHIS, the Texas Animal Health Commission, and Texas A&M AgriLife.

Confirmed cases in Texas

Texas counties affected

Cases still active

31 mi

Closest approach before first case

Latest confirmed total: 46 U.S. (45 in Texas, 1 in New Mexico) as of August 16, 2026, per USDA APHIS — 2 active and 44 resolved.

Confirmed cases by county

Hover a county for detail. USDA reports 16 affected counties; the 16 individually named in reporting are shown here. USDA does not publish exact per-county totals, so the map shows status, not case numbers.

Confirmed caseInfested zone (no confirmed case)None

How the outbreak has grown

From the first U.S. case in ~60 years to today.

Cumulative confirmed cases in Texas, per USDA APHIS. Steps mark the dates USDA published a revised total; between reports the count is carried forward.

Report a suspected case

Call the Texas Animal Health Commission at 1-800-550-8242 or contact your veterinarian immediately. Watch for maggots that burrow deeper into a wound, a foul odor, and wounds that enlarge over time. Early reporting is critical.

Outbreak timeline

Aug 18, 2026Confirmed case45 TX cases
Count reaches 46; Val Verde County confirms its first case
USDA’s dashboard listed 46 confirmed U.S. cases (45 in Texas, 1 in New Mexico) — 4 active, 42 inactive — after a sheep in Val Verde County, detected August 15, was added to the federal count August 16. It is the 16th Texas county with a case and only the second August confirmation, a marked slowdown from July’s 14. TAHC opened Infested Zone 19 in northern Val Verde, extending into parts of Crockett and Sutton; parts of 23 counties remain under movement restrictions.
Aug 6, 2026Confirmed case44 TX cases
Count reaches 45; sheep case in Terrell County opens August
USDA’s dashboard listed 45 confirmed U.S. cases (44 in Texas, 1 in New Mexico) — 13 active, 32 inactive — after a sheep in Terrell County was confirmed August 5, the county’s fifth case and the first new detection since July 31. TAHC issued a modified order for Pecos and Terrell counties the same day; the infested zone still spans 23 counties.
Aug 3, 2026Confirmed case43 TX cases
Count reaches 44; Brewster adds two cases, infested zone extends to Presidio
USDA’s dashboard listed 44 confirmed U.S. cases (43 in Texas, 1 in New Mexico) — 12 active, 32 inactive — after cattle in Brewster County were confirmed July 29 and 30 and a sheep in Pecos County on July 31. TAHC’s July 30 order extended the infested zone into Presidio County, bringing movement restrictions to parts of 23 counties.
Jul 25, 2026Confirmed case41 TX cases
Count reaches 42; Jim Hogg, Pecos and Uvalde added to the case map
USDA’s dashboard listed 42 confirmed U.S. cases (41 in Texas, 1 in New Mexico) after goats in Sutton County were confirmed July 21. A review of USDA’s case-level data added three counties that had been carried as quarantine-only: Jim Hogg (June 26), Pecos (June 29, the first Texas dog case) and Uvalde (June 29). Movement restrictions cover parts of 22 counties, and interstate pet-transport rules began squeezing Texas animal shelters.
Jul 22, 2026Confirmed case40 TX cases
Count hits 41; Starr County declares disaster, Schleicher confirms first case
USDA’s dashboard listed 41 confirmed U.S. cases (40 in Texas, 1 in New Mexico) — 12 active, 29 inactive. Starr County’s first case, a calf north of Roma, drew a county disaster declaration on July 20; Schleicher County confirmed its first detection July 19, and a goat case was confirmed in Gillespie County. USDA reported 591 screwworm traps now deployed across Mexico.
Jul 14, 2026Confirmed case34 TX cases
Cases reach 35 nationally as July slows; Brewster County added
USDA data released July 12 put the outbreak at 35 confirmed cases (34 in Texas, 1 in New Mexico) — 19 active, 16 inactive. Crockett County leads with 11 cases; a new detection landed in Brewster County. Just four new infections in early July, versus 31 in June, hinted the response may be gaining ground.
Jul 10, 2026Confirmed case31 TX cases
Outbreak reaches 32 cases across 12 Texas counties
USDA confirmed 32 infestations total (31 in Texas, 1 in New Mexico) spanning 12 Texas counties across 23 premises. Crockett County has emerged as the epicenter, reported to lead the state with about eight cases.
Jul 4, 2026Confirmed case30 TX cases
Cases climb to 31; spread to Crockett County
USDA confirmed 31 infestations total (30 in Texas, 1 in New Mexico) — the latest two sheep in Crockett County, ~300 miles southwest of Dallas.
Jun 29, 2026Milestone25 TX cases
US and Mexico open Metapa, Chiapas sterile-fly plant
The $50M+ facility will produce up to 100M sterile flies weekly for the cross-border fight.
Jun 27, 2026Confirmed case25 TX cases
Cases rise to 25; ground-vehicle fly releases begin
USDA began its first ground-vehicle sterile fly releases amid 8,000+ traps and 59,000+ samples.
Jun 22, 2026Policy12 TX cases
USDA commits $105M to 40 Grand Challenge projects
Funding from 226 proposals included Texas A&M electron-beam sterilization research.
Jun 21, 2026Policy12 TX cases
Abbott disaster declaration covers all 254 counties
Texas launched screwworm.texas.gov as the FAO and IAEA opened a five-year sterile-insect project spanning 20+ countries.
Jun 18, 2026Policy11 TX cases
Texas secures federal funding for 15 more inspectors
A USDA cooperative agreement funded 15 new TAHC positions as 13 counties sat under quarantine.
Jun 16, 2026Confirmed case11 TX cases
Spread reaches ~200 miles to Sutton and Tom Green
USDA confirmed at least 12 cases (mostly cattle, plus goats and a dog) spanning ~200 miles from the initial Zavala site.
Jun 13, 2026Policy
Abbott launches free NWS inspector training
A free four-hour AgriLife Learn certification course opened to expand the pool of trained inspectors.
Jun 13, 2026Confirmed case11 TX cases
San Angelo / Tom Green declare disaster; 11 cases
A bovine case near Grape Creek brought the outbreak to 11 cases; quarantine grew to 12 counties.
Jun 8, 2026Policy6 TX cases
Abbott activates State EOC; six cases, 10-county zone
With new detections in La Salle, Gillespie and Edwards counties, Gov. Abbott raised the State Emergency Operations Center to Level II.
Jun 3, 2026Confirmed case1 TX case
First U.S. case in 60 years — Zavala County
USDA confirmed NWS in a three-week-old calf near La Pryor — the first U.S. case since eradication in the 1960s. TAHC established an infested zone.
May 30, 2026Approach31 mi from border
Within 31 miles of Texas; CBP launches border campaign
The closest approach — 31 miles — prompted a bilingual CBP awareness campaign across Laredo-area ports of entry.
May 29, 2026Milestone
USDA opens Knipling-Bushland research lab in Kerrville
A new 52,000-sq-ft federal livestock-insects lab opened in Kerrville as Mexico reported cases climbing in Nuevo León and Coahuila.
May 27, 2026Approach57 mi from border
Closest yet — 57 miles, found in a domestic cat
A confirmation in a 16-month-old cat put the pest 57 miles from the border as 100M sterile flies were released weekly.
May 15, 2026Policy
Texas Senate convenes emergency hearing
The Senate agriculture committee heard testimony from USDA, TPWD, Texas A&M and TAHC on the $750M Moore Air Base sterile-fly facility.
May 10, 2026Policy
USDA extends sterile-fly releases to Eagle Pass
Sterile fly operations expanded into Maverick County, shifting from reactive containment to a proactive barrier.
May 5, 2026Approach119 mi from border
Jumps to a new Mexican state — Coahuila, 119 miles out
A May 1 Coahuila detection marked a westward expansion; TDA expanded trapping with Swormlure.
Apr 30, 2026Policy60 mi from border
FDA authorizes Negasunt Powder for emergency use
The FDA issued an Emergency Use Authorization for a topical powder to prevent and treat infestations — its second screwworm EUA that week.
Apr 28, 2026Policy
Florida restricts livestock from six Texas counties
Florida required enhanced screening for animals from Zapata, Jim Hogg, Starr, Hidalgo, Webb and Brooks counties — before any U.S. case.
Apr 24, 2026Approach60 mi from border
Advances to 60 miles; Miller activates emergency response
A Nuevo León detection just 60 miles from the border — a 30-mile advance in two weeks — triggered state emergency protocols.
Apr 16, 2026Policy90 mi from border
USDA APHIS releases updated Response Playbook
APHIS published a revised playbook covering surveillance, spread reduction and business continuity.
Apr 14, 2026Approach90 mi from border
Detected 90 miles from Texas in Nuevo León
Texas Agriculture Commissioner Sid Miller warned of a detection ~90 miles south of the border — the northernmost to that point.

Frequently asked questions

Official sources

Case counts and county lists are compiled from our ongoing screwworm coverage, each article citing its primary sources. Figures reflect the most recent USDA APHIS total as of August 23, 2026 and are updated as new counts are published.

Protect your property

Screwworm is a livestock and wildlife emergency, but Texas homes face year-round pest pressure. Find licensed help and pest guides:

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