A month after Texas reported the first New World screwworm case in decades, the U.S. total has reached 29. USDA confirmed two additional cases June 30, while Texas has quarantined 21 counties to restrict animal movement and slow further spread.
By the end of June, Texas was no longer treating screwworm as a distant worry. Two new confirmed cases—reported by the U.S. Department of Agriculture on Tuesday, June 30—pushed the national total to 29, roughly a month after Zavala County, Texas, reported the first case in the U.S. in decades.
The New World screwworm outbreak is still concentrated in Texas, where the state remains the only one reporting active cases. The added confirmations deepen the pressure on officials trying to stop a parasite that can turn small wounds into outbreaks.
USDA reported the two new cases as part of the continuing escalation. One of them involved a domestic dog in Pecos County—described as the first confirmed dog case in Texas—while another case added to the totals in Uvalde County, which also reported its first case.
Texas has now tallied 28 cases in total, with 22 active and six inactive, according to the confirmation dates tracked by USDA.
The stakes sit in the biology. The New World screwworm is a parasitic fly whose larvae feed on the living tissue of warm-blooded animals. including livestock. pets. and wildlife. When infestations begin, a female fly lays eggs on a wound or body opening. Eggs hatch into larvae that burrow into the wound and feed on living tissue. After about seven days of feeding, the larvae drop to the ground, burrow into the soil, and pupate.
For ranchers, pet owners, and wildlife officials, the timeline matters—because the feeding period is long enough for harm to spread before symptoms are caught.
From June 30 onward, each new confirmed location reshaped the map of risk across the state. The 29th U.S. case, earlier confirmed in New Mexico, has since been classified as inactive by USDA.
In Texas, the case-by-case record shows how the outbreak spread through multiple animal types and counties over the month. USDA’s dashboard lists the following confirmation dates:
June 30: One inactive domestic dog case in Pecos County. June 29: One active domestic cattle case in Uvalde County. June 27: One active domestic cattle case in Crockett County. June 26: One active domestic cattle case in Jim Hogg County. June 24: One active domestic cattle case in Medina County; one active domestic sheep case in Edwards County; four active domestic sheep cases in Crockett County. June 23: Three active domestic cattle cases in
Terrell County. June 22: One active domestic goat case in Terrell County. June 21: Two active domestic cattle cases in Edwards County. June 20: One active domestic sheep case in Crockett County. June 12: One inactive domestic sheep case in Sutton County. June 11: Two active domestic goat and cattle cases in Edwards County; one active domestic cattle case in Tom Green County; one inactive domestic cattle case in Zavala County. June 9: One active
domestic cattle case in Edwards County. June 8: One inactive domestic goat case in Gillespie County; one active domestic cattle case in La Salle County. June 7: One inactive domestic cattle case in La Salle County. June 5: One active domestic cattle case in Zavala County. June 3: One inactive domestic cattle case in Zavala County.
The outbreak began as a national anomaly. Officials say it was the first in the U.S. since 1966. Texas has been the only state reporting cases, including the first confirmed infection in a domestic dog, tied to the Pecos County finding.
While officials tracked the spread, the containment effort accelerated in parallel.
Texas Animal Health Commission quarantine zones tighten movement
Texas has quarantined parts of 21 counties across West, South and Central Texas. The quarantine is designed to restrict animal movement in an effort to prevent additional spread.
The Texas Animal Health Commission set the quarantine effective dates in phases. Zone 1 became effective June 3 with Uvalde and Zavala counties. Zone 2 became effective June 7 with La Salle and Webb counties. Zone 3 became effective June 9 with Gillespie, Kerr and Kimble counties. Zone 4 became effective June 10 with Edwards, Sutton and Val Verde counties. Zone 5 became effective June 12 with Tom Green and Coke counties.
Subsequent zones expanded the ring: Zone 6 became effective June 13 with Kimble, Schleicher and Sutton counties. Zone 7 became effective June 20 with Crockett, Schleicher, Val Verde, Terrell and Sutton counties. Zone 8 became effective June 22 with Terrell and Pecos counties. Zone 9 became effective June 24 with Bandera, Medina and Uvalde counties. Zone 10 became effective June 26 with Jim Hogg, Starr and Zapata counties. Zone 11 became effective June 30 with Uvalde County.
Under the orders that established the quarantines, the quarantine remains in effect until the commission lifts it.
The outbreak is defined by how quickly it can take hold—yet the response depends on when officials can stop movement and ensure infected animals are handled properly. USDA also classifies cases as inactive when the animal has fully recovered or. in cases where treatment was not performed. when appropriate measures have been taken to prevent spread. such as the proper disposal of the dead. infested animal.
Adult New World screwworm flies are also identifiable by physical traits described by USDA: orange eyes. a metallic blue or green body. and three dark stripes across the back. The telltale signs of infection include growing wounds or lesions and the presence of feeding maggots on still-alive animals.
On the ground. officials have been working against a clock that runs from egg-laying to feeding and pupation—while the case count continues to climb. With Texas still reporting active cases and with quarantines now covering 21 counties. the next questions are simple and immediate: how quickly can movement restrictions slow new detections. and whether the inactive classifications begin to outpace the active ones.
New World screwworm Texas Animal Health Commission USDA quarantines cattle sheep goats domestic dog Pecos County Uvalde County livestock health infectious disease