# US-Mexico screwworm outbreak: containment and human impact

> Live situation record from CLSTR: https://clstr.news/situations/rising-crossborder-pest-and-disease-outbreaks-spur-biosecurity-measures-in-mexico-and-the-united-sta
> Updated: 2026-09-19T23:00:10.000Z. Sources: 456. Developments: 144.

The New World screwworm outbreak continues to impact the U.S.–Mexico border, with containment efforts facing new biosecurity challenges. While the USDA-APHIS has lifted the infested zone in New Mexico following a single confirmed case in a dog on 7 June 2026, the parasite remains a threat near the border. The resurgence, which began in 2023, has resulted in over 144,000 animal cases and 1,100 human cases across the region.

In the United States, a second case has been confirmed in a horse in Grant County, New Mexico. Despite this, U.S. Agriculture Secretary Brooke Rollins announced that the Santa Teresa port is scheduled to reopen for Mexican cattle imports on 24 September, following a closure of over a year. The USDA has invested over $1.3 billion in containment, including drone monitoring and the release of more than one billion sterile flies.

In Mexico, livestock management remains critical. Sonora reports approximately 59 cases across 11 municipalities, including Hermosillo, with weekly releases of over 12 million sterile flies. In the State of Mexico, biological trapping barriers have prevented an estimated 29 million larvae from hatching. Tamaulipas reports 24 active cases, while cattle exports from Coahuila to the U.S. may face delays of up to four months due to sanitary protocols.

Human impact persists, with Veracruz reporting the highest number of human cases in Mexico for 2026, totaling 113 confirmed cases as of 11 September—roughly 20 percent of the 564 national cases. Veracruz has also recorded one death. Other states with significant human cases include Chiapas, Oaxaca, Puebla, Yucatán, Guerrero, and San Luis Potosí.

## Claims

- There are 1,963 active cases of screwworm in Mexico. (disputed by 4 sources)
- There are 1,965 active cases of screwworm in 29 Mexican entities. (disputed by 3 sources)
- The Chihuahua Secretariat of Rural Development has distributed over 4,000 preventive kits to livestock producers. (disputed by 3 sources)
- The state has acquired 9,000 preventive kits for livestock producers. (disputed by 3 sources)
- As of August 5, 2026, there were 1,929 active cases recorded nationally in Mexico. (disputed)
- The first case of cattle screwworm in Sonora was detected in a bovine in the Munihuasa community, Álamos municipality. (corroborated by 8 sources)
- Authorities established a 20-kilometer sanitary perimeter around the detection site in Álamos. (corroborated by 8 sources)
- Governor Maru Campos presented a new sanitary protocol to combat Cattle Screwworm across 67 municipalities in Chihuahua. (corroborated by 7 sources)
- Sader released 14,970,000 sterile flies in Chihuahua between July 27 and August 11. (corroborated by 6 sources)
- Senasica confirmed the first case of cattle screwworm in Hidalgo del Parral on July 13. (corroborated by 6 sources)
- Sonora authorities activated a sanitary containment operation following the first confirmed case of cattle screwworm in the state. (corroborated by 6 sources)

## Timeline

### 2026-09-19: New World screwworm resurfaces in New Mexico

The New World screwworm has resurfaced in New Mexico, complicating plans to reopen a major U.S. port for Mexican cattle imports following recent livestock infestations.

6 sources. https://clstr.news/cluster/new-world-screwworm-resurfaces-in-new-mexico

### 2026-09-18: New Mexico screwworm case confirmed ahead of Santa Teresa port reopening

A New World screwworm infestation in a New Mexico horse occurs just before the Santa Teresa port is set to reopen for Mexican cattle imports on September 24.

3 sources. https://clstr.news/cluster/new-mexico-screwworm-case-confirmed-ahead-of-santa-teresa-port-reopening

### 2026-09-15: Veracruz reports highest number of human screw-worm cases in Mexico

Veracruz reports 113 human cases of screw-worm myiasis in 2026, the highest in Mexico, accounting for 20 percent of the nation's total cases.

2 sources. https://clstr.news/cluster/veracruz-reports-highest-number-of-human-screw-worm-cases-in-mexico

### 2026-09-15: Mexico manages cattle maggot outbreaks across multiple states

Mexico manages cattle maggot outbreaks in Sonora, Tamaulipas, and Estado de México through sterile fly releases and sanitary barriers, while Coahuila faces export delays to the U.S.

9 sources. https://clstr.news/cluster/screwworm-outbreaks-affect-livestock-in-sonora-and-estado-de-mxico

### 2026-09-12: Coahuila reports 38 screwworm cases, including two in Monclova

Coahuila, Mexico, reports 38 cases of screwworm, including two in Monclova. Authorities are launching preventive medication campaigns to protect livestock and pets from the parasite.

3 sources. https://clstr.news/cluster/coahuila-reports-38-screwworm-cases-including-two-in-monclova

### 2026-09-05: Horse smuggling threatens U.S. efforts to contain New World screwworm

Illegal horse smuggling across the U.S.-Mexico border threatens efforts to contain the New World screwworm, a parasite that has recently returned to the region after decades of eradication.

2 sources. https://clstr.news/cluster/horse-smuggling-threatens-us-efforts-to-contain-new-world-screwworm

### 2026-09-05: Mexico combats screwworm outbreaks in Coahuila and Chihuahua

Mexican states Coahuila and Chihuahua are using sterile fly releases and sanitary protocols to combat screwworm outbreaks in livestock and protect cattle export opportunities to the United States.

2 sources. https://clstr.news/cluster/mexico-combats-screwworm-outbreaks-in-coahuila-and-chihuahua

### 2026-09-02: Secretariat of Rural Development warns against improper Cattle Screwworm treatment

Mexico's Secretariat of Rural Development warns livestock producers against using harmful home remedies to treat Cattle Screwworm wounds, urging professional veterinary consultation instead.

5 sources. https://clstr.news/cluster/secretariat-of-rural-development-warns-against-improper-cattle-screwworm-treatment

### 2026-09-02: Mexico inspects 80,000 cattle shipments to combat screw worm

Mexico has inspected over 80,000 cattle shipments to control the cattle screw worm pest, detecting 222 cases primarily in Chiapas and Tabasco to prevent national spread.

8 sources. https://clstr.news/cluster/mexico-inspects-80000-cattle-shipments-to-combat-screw-worm

### 2026-09-02: New World screwworm zone in New Mexico released by USDA

USDA has lifted the New World screwworm infested zone in New Mexico following successful containment, even as a new case of the parasitic fly is detected in Mexico near the U.S. border.

3 sources. https://clstr.news/cluster/new-world-screwworm-zone-in-new-mexico-released-by-usda

### 2026-09-01: Mexico reports fourth death from screw-worm parasite in 2026

Mexico reports its fourth death from the screw-worm parasite in 2026, with the latest fatality occurring in Veracruz. The country has seen 516 cases so far this year.

6 sources. https://clstr.news/cluster/mexico-reports-fourth-death-from-screw-worm-parasite-in-2026

### 2026-08-30: New Mexico screwworm infested zone lifted by USDA

USDA APHIS has lifted the New World screwworm infested zone in New Mexico after no new cases were detected since June, allowing for the normal movement of livestock and pets.

3 sources. https://clstr.news/cluster/new-mexico-screwworm-infested-zone-lifted-by-usda

### 2026-08-30: Mexico establishes scientific council to combat Cattle Screwworm

Mexico has launched a Technical-Scientific Council to transition its Cattle Screwworm strategy from an emergency response to a permanent national campaign using biotechnology and AI.

5 sources. https://clstr.news/cluster/mexico-establishes-scientific-council-to-combat-cattle-screwworm-1

### 2026-08-29: Mexico combats screwworm outbreak to stabilize livestock exports

Mexico is using sterile fly releases to combat a screwworm outbreak in Chihuahua and Sonora, aiming to stabilize livestock exports and potentially reopen more border ports to the United States.

4 sources. https://clstr.news/cluster/mexico-combats-screwworm-outbreak-to-stabilize-livestock-exports

### 2026-08-27: Mexico scales up national campaign to combat cattle screwworm outbreak

Mexico is transitioning its screwworm response to a permanent national campaign as outbreaks continue in Sonora and Chihuahua, including confirmed human cases in Sinaloa.

16 sources. https://clstr.news/cluster/chihuahua-maintains-sanitation-funding-to-combat-screwworm-outbreak

### 2026-08-26: Sonora detects first case of New World Screwworm

The first case of New World Screwworm has been detected in Sonora, Mexico, prompting new sterile fly facility investments in Texas and Arizona.

3 sources. https://clstr.news/cluster/sonora-detects-first-case-of-new-world-screwworm

### 2026-08-25: Mexico reports 602 human cases of screw-worm infestation

Mexico reports 602 human cases of screw-worm (Cochliomyia hominivorax) across 25 states, primarily affecting men and seniors in rural areas.

4 sources. https://clstr.news/cluster/mexico-reports-602-human-cases-of-screw-worm-infestation

### 2026-08-22: Mexico's Comisión Permanente urges action against screwworm parasite

Mexico's Comisión Permanente has urged Sader and Senasica to intensify efforts to control the screwworm parasite, which has caused over 33,000 cases since late 2024.

6 sources. https://clstr.news/cluster/mexicos-comisin-permanente-urges-action-against-screwworm-parasite

### 2026-08-17: Sonora confirms first screwworm case, triggering sanitary protocols

The first screwworm case in Sonora has left only two Mexican states free of the parasite. Authorities have implemented a 20km sanitary perimeter and released sterile flies to contain the infestation.

31 sources. https://clstr.news/cluster/jurez-implements-prevention-plan-for-screw-worm-fly

### 2026-08-12: New World screwworm outbreak threatens Mexico-US border

Authorities are monitoring New World screwworm outbreaks in Mexico that threaten livestock and the US border, while Irapuato officials implement new security strategies following an academic evaluation.

14 sources. https://clstr.news/cluster/irapuato-authorities-investigate-volkswagen-dealership-collapse

### 2026-08-12: Chihuahua implements sanitary protocol to combat cattle screwworm

Chihuahua has implemented a new sanitary protocol and released nearly 15 million sterile flies to combat the cattle screwworm outbreak across 67 municipalities.

22 sources. https://clstr.news/cluster/agricultural-council-warns-of-biotechnology-needs-in-mexico

### 2026-08-10: New World screwworm re-emerges in Mexico and US

The New World screwworm is re-emerging in Mexico and the US, causing human infestations and livestock damage. Researchers are exploring CRISPR-based sterile insect technology to aid eradication efforts.

4 sources. https://clstr.news/cluster/new-world-screwworm-re-emerges-in-mexico-and-us

### 2026-08-10: Mexico implements sanitary barriers to combat screwworm spread

Mexico is deploying millions of sterile flies and establishing new sanitary barriers in Chihuahua and the State of Mexico to contain the spread of the screwworm and prevent myiasis.

6 sources. https://clstr.news/cluster/mexico-implements-sanitary-barriers-to-combat-screwworm-spread

### 2026-08-07: Cattle screwworm outbreak triggers sanitary measures across Mexico

Mexico is battling a widespread cattle screwworm outbreak, with nearly 2,000 active cases reported. Authorities are using sterile fly dispersion and intensified inspections to contain the pest's spread.

16 sources. https://clstr.news/cluster/sinaloa-ramps-up-response-to-cattle-worm-outbreak-over-3500-animals-inspected

### 2026-08-05: Mexico expands sterile fly program to combat bovine screwworm

Mexico advances a sterile‑fly campaign against the bovine screwworm, adding new patents, releasing millions of sterile insects, urging the public not to kill them, and seeking to include Zacatecas in the effort

4 sources. https://clstr.news/cluster/mexico-advances-fight-against-cattle-screwworm-with-new-trap-and-expanded-sterilefly-program

### 2026-08-05: Mexico's Cattle Worm Outbreak Reaches 77 Cases in Chihuahua, 644 in Guanajuato

Mexico reports 77 cattle worm cases in Chihuahua and 644 total in Guanajuato, with 100 active, as authorities deploy sterile flies and surveillance to contain the outbreak.

8 sources. https://clstr.news/cluster/mexicos-cattle-worm-outbreak-reaches-77-cases-in-chihuahua-644-in-guanajuato

### 2026-07-31: Mexico steps up screwworm fly control as cases climb in Puebla and Chihuahua

Mexico intensifies screwworm fly control as cases surge in Puebla (172) and Chihuahua (41), deploying sterile flies, training producers, and expanding wildlife surveillance.

12 sources. https://clstr.news/cluster/mexico-deploys-sterile-fly-program-to-combat-cattle-screwworm

### 2026-07-28: Gusano barrenador outbreak spreads across Mexican states, prompting sterilized‑fly releases and US cattle‑export pause

Mexico’s gusano barrenador parasite spreads in Chihuahua, Zacatecas, Coahuila and other states; sterile‑fly releases and free inspections are underway, and the US USDA plans to reopen a cattle export crossing,‑

18 sources. https://clstr.news/cluster/cochliomyia-hominivorax-worm-outbreak-spreads-in-chihuahua-and-coahuila-first-pet-case-reported

### 2026-07-27: Mexico reports surge in human myiasis cases and first fatality

Mexico logged 361 myiasis cases in early 2026, including three deaths, with hotspots among elderly men in rural Sierra regions; 37 cases were reported in Yucatán and three in Morelos, prompting health warnings.

5 sources. https://clstr.news/cluster/yucatn-sees-37-human-screwworm-cases-amid-mexicos-500plus-infections

### 2026-07-26: USDA ramps up response to New World screwworm outbreak in Texas

USDA confirmed New World screwworm in Texas (June 3, 2026), 27 cases across TX/NM by June 30, and is boosting inspections and treatments as active cases fall to ten, affecting livestock‑border policies.

8 sources. https://clstr.news/cluster/usda-responds-to-new-world-screwworm-outbreak-with-stricter-livestock-inspection-protocols

### 2026-07-23: U.S. launches GMO screwworm fly trials in Panama to combat livestock pest

U.S. scientists begin outdoor trials of GMO sterile screwworm flies in Panama to combat a livestock parasite threatening Texas cattle and $1 bn in losses.

7 sources. https://clstr.news/cluster/us-launches-gmo-screwworm-fly-trials-in-panama-to-combat-livestock-pest

### 2026-07-22: Mexico's screw-worm fly outbreak spreads across northern states

Screw‑worm fly infections rise in Mexico, with a human case in Jalisco, dozens of animal cases, and spread to six northern states, triggering a US cattle import ban and costly control efforts.

6 sources. https://clstr.news/cluster/jalisco-reports-third-human-screwworm-case-and-35-infected-dogs

### 2026-07-21: USDA Confirms 41 New World Screwworm Cases in U.S., Expands Eradication Program

USDA confirms 41 New World screwworm cases in Texas and New Mexico, expands sterile‑fly releases and border traps to protect livestock and contain the pest.

6 sources. https://clstr.news/cluster/usda-confirms-dozens-of-new-world-screwworm-cases-in-texas-and-new-mexico

### 2026-07-19: Wisconsin Tightens Livestock Import Rules to Block New World Screwworm

Wisconsin imposes stricter import rules for livestock to prevent the New World Screwworm, requiring detailed veterinary certificates, permits and biosecurity measures effective July 21.

3 sources. https://clstr.news/cluster/wisconsin-tightens-livestock-import-rules-to-block-new-world-screwworm

### 2026-07-18: Mexico's screw-worm fly spreads to 28 states, triggers health and livestock alerts

Mexico's screw-worm fly now affects 28 states, causing $400‑500 M in livestock losses, human cases, export bans and prompting sterile‑fly releases and climate‑risk warnings.

16 sources. https://clstr.news/cluster/puerto-vallarta-reports-first-human-livestock-fly-infection-as-autism-center-construction-begins

### 2026-07-17: US livestock sector emphasizes disease surveillance after screwworm case and hatchery microbe findings

US producers are urged to monitor for New World screwworm after a Texas case, while a Zoetis study flags ongoing Aspergillus contamination in hatcheries, stressing tighter sanitation and surveillance.

2 sources. https://clstr.news/cluster/us-livestock-sector-emphasizes-disease-surveillance-after-screwworm-case-and-hatchery-microbe-findin

### 2026-07-16: New World Screw Worm Returns to US Livestock in Texas and New Mexico

The New World Screw Worm parasite reappeared in U.S. livestock after 60 years, with confirmed cases in Texas and New Mexico, prompting USDA-led emergency monitoring and control measures.

2 sources. https://clstr.news/cluster/new-world-screw-worm-returns-to-us-livestock-in-texas-and-new-mexico

### 2026-07-15: Screw-worm fly threatens US cattle, says Polish beef sector safe

The US screw-worm fly outbreak threatens cattle with billions in losses, but Polish beef experts say it poses no risk to Poland.

2 sources. https://clstr.news/cluster/screw-worm-fly-threatens-us-cattle-says-polish-beef-sector-safe

### 2026-07-15: New World Screwworm Sparks US Import Restrictions and Mexico Trade Halt

New World screwworm reappears near the US‑Mexico border, prompting USDA import bans, sterile‑fly releases, Wisconsin’s tightened animal import rules, and Mexico’s halt to US live‑animal imports, with potential

5 sources. https://clstr.news/cluster/new-world-screwworm-reaches-texas-sparking-us-livestock-risks-and-trade-bans

### 2026-07-15: Mexico's cattle worm outbreak in Chihuahua threatens $2 billion in exports

Mexico’s first cattle‑worm case in Chihuahua triggers a 20‑km/40‑km sanitary zone, $2 bn export losses risk, US border closure, and nationwide control measures including sterile‑fly releases.

17 sources. https://clstr.news/cluster/mexico-cattle-worm-outbreak-spreads-to-28-states

### 2026-07-14: New World screwworm outbreak returns to Texas, spreads to New Mexico

The New World screwworm has returned to Texas and New Mexico, with 33 animal cases and a new infested zone in Sutton County; officials warn of up to $1.8 billion in livestock losses.

5 sources. https://clstr.news/cluster/texas-livestock-report-new-world-screwworm-outbreak

### 2026-07-10: Yucatán launches phase‑two trap program to curb worm infestation harming livestock and humans

Yucatán expands its worm‑infestation control with 625 blue traps in 13 areas, addressing 2,259 animal cases and 36 human miasis infections, including one death.

3 sources. https://clstr.news/cluster/yucatn-launches-phasetwo-trap-program-to-curb-worm-infestation-harming-livestock-and-humans

### 2026-07-10: Mexico opens Chiapas sterile‑fly factory to curb cattle grub disease

Mexico’s new Chiapas sterile‑fly factory, funded by Mexico and the U.S., will produce up to 100 million sterile flies weekly to control the cattle grub fly and help reopen the U.S.–Mexico livestock border.

2 sources. https://clstr.news/cluster/mexico-opens-chiapas-sterilefly-factory-to-curb-cattle-grub-disease

### 2026-07-09: New World screwworm infestations reported in Texas, New Mexico and Mexico

New World screwworm cases have emerged in Mexico and across Texas and New Mexico, prompting alerts and monitoring in the US and Hawaii.

4 sources. https://clstr.news/cluster/us-monitors-rising-new-world-screwworm-cases-in-livestock-and-pets

### 2026-07-08: Texas faces dual invasive insect threats to cattle and pasture lands

Texas contends with a fast‑spreading pasture mealybug threatening cattle pastures and a resurging New World screwworm endangering livestock and pets, prompting urgent control measures.

4 sources. https://clstr.news/cluster/texas-faces-invasive-pest-threats-to-livestock-and-forage

### 2026-07-08: Mexico launches sterile‑fly release in Tamaulipas to combat screwworm

Mexico will begin releasing sterile flies from Tamaulipas, produced at a new Chiapas plant, to eradicate the screwworm affecting cattle; up to 100 million flies weekly aim to lift US trade bans.

12 sources. https://clstr.news/cluster/mexico-us-sterile-fly-facility-in-chiapas-aims-to-reopen-border

### 2026-07-07: Screwworm infestations surge in Panama, United States and Guatemala

Panama reports 55 human screwworm cases, the US confirms 32 livestock infections, and Guatemala inspects over 245,000 animals to curb the parasite.

4 sources. https://clstr.news/cluster/screwworm-infestations-surge-in-panama-united-states-and-guatemala

### 2026-07-07: Mexico reports hundreds of animal worm cases and dengue decline in Tabasco

Hidalgo logged 942 livestock screwworm cases and 14 human infections (one unrelated death); Tabasco saw 414 dengue cases, dropping to fourth nationally, with intensified vector control.

2 sources. https://clstr.news/cluster/mexico-reports-hundreds-of-animal-worm-cases-and-dengue-decline-in-tabasco

### 2026-07-06: Public health agencies train vector‑surveillance teams in Mexico and Spain

Mexico and Spain conducted training exercises to boost surveillance and response to screwworm and tiger‑mosquito threats, enhancing public‑health preparedness.

2 sources. https://clstr.news/cluster/public-health-agencies-train-vectorsurveillance-teams-in-mexico-and-spain

### 2026-07-05: Cochliomyia hominivorax worm infestation spreads across Mexico and reaches the United States

A re‑emergent screwworm fly infestation in Mexico, with over 28,000 animal cases, has spread to Texas and New Mexico, prompting border livestock restrictions and renewed biocontrol efforts.

3 sources. https://clstr.news/cluster/cochliomyia-hominivorax-worm-infestation-spreads-across-mexico-and-reaches-the-united-states

### 2026-07-04: Texas livestock threatened by invasive pasture mealybug and New World screwworm

Invasive pasture mealybug and New World screwworm are spreading across Texas, threatening forage and the $41 billion cattle industry, with limited control measures and ongoing containment efforts.

3 sources. https://clstr.news/cluster/new-world-screwworm-spreads-in-texas-threatening-cattle-and-poultry

### 2026-07-04: Veracruz reports surge in screw-worm fly (myiasis) cases

Veracruz has 70 confirmed screw‑worm fly (myiasis) cases, the second‑highest in Mexico, prompting health alerts and treatment guidance.

4 sources. https://clstr.news/cluster/veracruz-reports-surge-in-screw-worm-fly-myiasis-cases

### 2026-07-02: Four Human Myiasis Cases Confirmed in Querétaro, Mexico

Querétaro's health secretariat reports four human cases of screw‑worm myiasis in 2026, urging prompt medical care and heightened surveillance.

2 sources. https://clstr.news/cluster/four-human-myiasis-cases-confirmed-in-quertaro-mexico

### 2026-07-01: Coahuila health officials report first human myiasis case, warn of wound care

Coahuila confirms Mexico's first human myiasis case in an 84‑year‑old vet, urging wound care; Michoacán health officials warn of rain‑related mosquito risks and advise preventive measures.

2 sources. https://clstr.news/cluster/coahuila-health-officials-report-first-human-myiasis-case-warn-of-wound-care

### 2026-06-29: US and Mexico Expand Sterile Fly Program to Fight New World Screwworm

US and Mexico are scaling up a sterile‑fly program to contain the New World screwworm, with a new USDA facility in Mexico set to release 30 million flies by July amid 16 U.S. cases and potential billions in liv

5 sources. https://clstr.news/cluster/us-and-mexico-expand-sterile-fly-program-to-fight-new-world-screwworm

### 2026-06-28: Mexico and United States inaugurate sterile‑fly plant in Chiapas

Mexico’s President Claudia Sheinbaum and U.S. officials inaugurated a binational sterile‑fly plant in Chiapas that will produce 100 million insects weekly to fight the cattle grub worm, boosting livestock‑herd

2 sources. https://clstr.news/cluster/mexico-and-united-states-inaugurate-sterilefly-plant-in-chiapas

### 2026-06-27: Claudia Sheinbaum opens US‑Mexico sterile‑fly plant in Chiapas

President Sheinbaum opened a US‑Mexico sterile‑fly plant in Chiapas to fight the livestock‑killing screwworm, with $144 M joint investment, and delivered housing that adds ~1 % to Mexico’s GDP.

30 sources. https://clstr.news/cluster/sinaloa-governor-yeraldine-bonilla-delivers-sorghum-seed-to-3800-ranchers

### 2026-06-26: US livestock face rising New World Screwworm cases as Mississippi reports none

USDA reports 20 New World Screwworm detections, all in Texas and New Mexico, while Mississippi says none and readies a response plan for livestock.

2 sources. https://clstr.news/cluster/us-livestock-face-rising-new-world-screwworm-cases-as-mississippi-reports-none

### 2026-06-25: Mexico‑US Inaugurate Sterile Fly Plant in Chiapas to Combat Screwworm

Mexico and the U.S. opened a $61 M sterile‑fly plant in Chiapas on 27 June 2026, aiming to produce 100 M sterile flies weekly to curb the screwworm outbreak affecting livestock and trade.

21 sources. https://clstr.news/cluster/mexico-us-open-sterilefly-plant-in-chiapas-to-combat-screwworm

### 2026-06-25: New World Screwworm Detected in Texas Threatens Livestock and Pets

USDA confirms the first U.S. New World screwworm case in Texas, risking livestock, dairy supply and pet health; sterile‑male releases may be used to contain the fly.

5 sources. https://clstr.news/cluster/new-world-screwworm-detected-in-texas-threatens-livestock-and-pets

### 2026-06-25: Mexico and United States intensify response to screwworm outbreak in livestock

Mexico’s screwworm cases surged 83.5% to 30,500 by June, spreading into Texas where 20 US animal infections were confirmed; joint Mexico‑US investments fund new sterile‑fly plants and emergency measures.

9 sources. https://clstr.news/cluster/screwworm-parasite-resurfaces-in-us-and-mexico-prompting-massive-eradication-effort

### 2026-06-23: Veracruz legislators under scrutiny and worm outbreak threatens cattle and public health

Veracruz lawmakers face probe over a 3 million‑peso resource use while a screwworm outbreak adds 34 human cases, two deaths and threatens cattle trade, prompting US and Mexican health actions.

2 sources. https://clstr.news/cluster/veracruz-legislators-under-scrutiny-and-worm-outbreak-threatens-cattle-and-public-health

### 2026-06-23: Texas sees 16 New World Screwworm cases in livestock

USDA reports 16 New World screwworm cases in Texas and New Mexico livestock, urging vigilance to prevent spread.

5 sources. https://clstr.news/cluster/texas-sees-16-new-world-screwworm-cases-in-livestock

### 2026-06-22: Mexico cattle sector suffer price slump as worm-driven border closure bites

Mexican cattle producers face price drops as the cattle worm shuts the U.S. live‑cattle border, while packaged meat exports rise 30% after shifting to domestic finishing and a new sterile‑fly plant is slated to

4 sources. https://clstr.news/cluster/mexico-cattle-sector-suffer-price-slump-as-worm-driven-border-closure-bites

### 2026-06-22: US-Mexico Joint Inspection Targets Cattle Borer Worm in Coahuila

US and Mexican authorities conduct joint inspections in Coahuila to fight the cattle borer worm amid rising cases in Texas and Mexico, including human infections, and outline long‑term eradication plans.

8 sources. https://clstr.news/cluster/barren-worm-outbreak-hits-cattle-in-texas-and-mexico-trade-suspended

### 2026-06-22: New World screwworm cases rise to 15 in Texas

USDA reports 15 New World screwworm cases in Texas; sterile‑fly releases underway, with facilities planned in Mexico and Texas to avert a potential $1.8 billion livestock loss.

8 sources. https://clstr.news/cluster/new-world-screwworm-reemerges-in-texas-with-15-confirmed-cases

### 2026-06-21: US ground beef prices surge 20% amid screwworm outbreak and trade deal uncertainty

US ground beef prices have jumped over 20% due to a screwworm outbreak, drought and USMCA renewal uncertainty, prompting shoppers to shift to cheaper proteins.

2 sources. https://clstr.news/cluster/us-ground-beef-prices-surge-20-amid-screwworm-outbreak-and-trade-deal-uncertainty

### 2026-06-20: Veracruz reports surge in dengue cases and leads nation in human myiasis infections

Veracruz logged 354 dengue cases, one death, and a drop from 2025, while also leading Mexico with 69 human myiasis infections, prompting health warnings.

2 sources. https://clstr.news/cluster/veracruz-reports-surge-in-dengue-cases-and-leads-nation-in-human-myiasis-infections

### 2026-06-20: Coahuila Remains Free of Human Myiasis Cases Amid National Surge

Coahuila reports no human myiasis cases, only two infected dogs, while Mexico records 295 cases and two deaths; joint health‑rural actions focus on animal monitoring and wound hygiene.

2 sources. https://clstr.news/cluster/coahuila-remains-free-of-human-myiasis-cases-amid-national-surge

### 2026-06-19: Texas New World Screwworm Outbreak Triggers State Website and Shelter Safeguards

Texas governor launches a new screwworm information website as the state battles a New World screwworm outbreak, while shelters adopt tighter inspections, parasite treatments and face quarantine and interstate‑

2 sources. https://clstr.news/cluster/texas-new-world-screwworm-outbreak-triggers-state-website-and-shelter-safeguards

### 2026-06-19: Mexican livestock parasite outbreak deemed safe for meat consumption

Mexico says meat from cattle infected with the barrenador worm remains safe after treatment, while rising animal and human cases spur lawmakers to demand stronger federal and state parasite control.

3 sources. https://clstr.news/cluster/mexican-livestock-parasite-outbreak-deemed-safe-for-meat-consumption

### 2026-06-18: Veracruz reports 69 human cases of botfly (myiasis) in 2026

Veracruz logged 69 botfly myiasis cases in 2026, the highest state count, with no deaths; Mexico totals 412 cases and two deaths nationwide.

6 sources. https://clstr.news/cluster/veracruz-reports-69-human-cases-of-botfly-myiasis-in-2026

### 2026-06-18: USDA launches $105 million program to curb New World Screwworm in U.S. livestock

USDA funds $105 M for 40 projects, including drones and sterile flies, to fight New World Screwworm after 11‑12 cases in Texas and New Mexico; horse owners receive guidance and Arkansas tightens animal‑movement

4 sources. https://clstr.news/cluster/usda-launches-105-million-effort-to-combat-new-world-screwworm

### 2026-06-17: New World Screwworm Reappears in US, Prompting Veterinary Alerts and Beef Industry Concerns

USDA reports six New World Screwworm cases in Texas/New Mexico, prompting veterinary alerts and a costly government response amid modest beef‑price concerns.

2 sources. https://clstr.news/cluster/new-world-screwworm-reappears-in-us-prompting-veterinary-alerts-and-beef-industry-concerns

### 2026-06-17: US Beef Prices Surge as Screwworm Outbreak and USMCA Trade Talks Heighten Risks

US beef prices have risen over 20% as a screwworm outbreak spreads from Mexico, while USMCA trade talks create import uncertainty; USDA invests $105 M in bio‑security to contain the threat.

2 sources. https://clstr.news/cluster/us-beef-prices-surge-as-screwworm-outbreak-and-usmca-trade-talks-heighten-risks

### 2026-06-16: Mexico logs 295 human screwworm cases in 2026, sterile‑fly plant delayed

Mexico's health ministry reports 295 human screwworm infections in early 2026, chiefly in Veracruz, with two deaths, while a sterile‑fly plant in Chiapas is 75% complete but not yet operational.

2 sources. https://clstr.news/cluster/mexico-logs-295-human-screwworm-cases-in-2026-sterilefly-plant-delayed

### 2026-06-16: USDA allocates $105 M to fight New World screwworm outbreak

USDA has allocated $105 M to 40 projects, including Texas A&M research, AI drone partnerships, and veterinary resources, to contain New World screwworm cases in Texas and New Mexico, while ranchers and PA/NJ ag

6 sources. https://clstr.news/cluster/new-world-screwworm-spread-prompts-usdadhs-funding-and-state-quarantines

### 2026-06-13: New World screwworm parasite resurges in US livestock

USDA reports 11 New World screwworm cases in Texas and New Mexico, prompting intensified surveillance and sterile‑fly releases to protect livestock and prevent spread to Europe.

2 sources. https://clstr.news/cluster/new-world-screwworm-outbreak-spreads-to-livestock-in-the-us

### 2026-06-13: New World screwworm prompts US emergency drug approval and Colorado movement restrictions

The FDA approved emergency use of nitenpyram for New World screwworm in pets, and Colorado imposed strict animal‑movement inspections to block the parasite’s spread after recent Texas and New Mexico cases.

2 sources. https://clstr.news/cluster/new-world-screwworm-prompts-us-emergency-drug-approval-and-colorado-movement-restrictions

### 2026-06-13: New World screwworm outbreak threatens Texas cattle industry

Texas monitors a New World screwworm resurgence with nine livestock cases; USDA declares disaster, California tightens animal entry rules, and a sterile‑fly facility opens to curb the threat to cattle and beef.

4 sources. https://clstr.news/cluster/new-world-screwworm-outbreak-threatens-texas-cattle-industry

### 2026-06-13: State of Mexico calls for extra funds to battle livestock botfly outbreak

State of Mexico deputy Javier Cruz seeks more funding to combat a cattle botfly, citing nine active cases and a total of 289 across 40 municipalities, with coordination extending to neighboring states.

2 sources. https://clstr.news/cluster/state-of-mexico-calls-for-extra-funds-to-battle-livestock-botfly-outbreak

### 2026-06-12: US screwworm outbreak threatens Texas cattle industry

A screwworm fly outbreak in Texas and New Mexico has infected six cattle, prompting USDA and CDC emergency actions and plans to boost sterile‑fly releases to curb spread.

2 sources. https://clstr.news/cluster/us-screwworm-outbreak-threatens-texas-cattle-industry

### 2026-06-11: US Agriculture Secretary Brooke Rollins denies aid cuts linked to screwworm resurgence

US Agriculture Secretary Brooke Rollins said aid cuts did not trigger the screwworm outbreak in Texas and New Mexico, noting USDA staff rose from 10 to over 120 and warning of possible multi‑billion‑dollar C‑c​

2 sources. https://clstr.news/cluster/us-agriculture-secretary-brooke-rollins-denies-aid-cuts-linked-to-screwworm-resurgence

### 2026-06-11: US detects Barren Worm in Texas, prompting Mexico to halt live cattle imports

USDA reports a bovine screwworm case in Texas; Mexico suspends live cattle imports, citing illegal cattle smuggling and disease risk, as experts warn of billions‑dollar losses.

3 sources. https://clstr.news/cluster/us-detects-barren-worm-in-texas-prompting-mexico-to-halt-live-cattle-imports

### 2026-06-11: USDA Mobilizes Against New World Screwworm Outbreak in Texas and New Mexico

USDA confirms New World screwworm in Texas and New Mexico, creates quarantine zones, releases sterile flies, fast‑tracks treatments and FDA authorizes emergency drug for pets.

9 sources. https://clstr.news/cluster/usda-ramps-up-response-to-screwworm-outbreak-in-texas-and-new-mexico

### 2026-06-11: US CDC launches emergency response to screwworm fly outbreak in livestock

The US CDC activated a Level 3 emergency response after detecting the New World screwworm fly in cattle, a Texas goat and a New Mexico dog, coordinating with the USDA to monitor and contain the parasite.

2 sources. https://clstr.news/cluster/us-cdc-launches-emergency-response-to-screwworm-fly-outbreak-in-livestock

### 2026-06-11: Minnesota Beef Prices Face Potential Rise Amid Texas Screwworm Outbreak

Texas’s New World screwworm outbreak may push up Minnesota beef prices, though local supply could limit the impact.

4 sources. https://clstr.news/cluster/minnesota-beef-prices-face-potential-rise-amid-texas-screwworm-outbreak

### 2026-06-10: Xalapa pet worm infestation threatens stray animals

Protectors in Xalapa report a surge in screwworm myiasis in stray dogs and cats, warning that untreated open wounds can kill animals within hours.

2 sources. https://clstr.news/cluster/xalapa-animal-rescue-groups-warn-of-deadly-parasite-in-stray-pets

### 2026-06-10: US Agriculture Secretary Rollins addresses New World screwworm outbreak

US Agriculture Secretary Brooke Rollins reported six screwworm cases, said the outbreak is under control, and noted a $1.3 bn USDA response, while a Trump official blamed Biden’s immigration policies for the re

6 sources. https://clstr.news/cluster/us-agriculture-secretary-rollins-addresses-new-world-screwworm-outbreak

### 2026-06-10: New World screwworm resurfaces in US Southwest, prompting statewide response

USDA reports a second New World screwworm case in New Mexico after Texas, linking spread to illegal cattle smuggling. Sterile‑fly releases and state alerts aim to contain a threat that could cost the beef trade

4 sources. https://clstr.news/cluster/new-world-screwworm-resurfaces-in-us-southwest-prompting-statewide-response

### 2026-06-10: Texas Gov. Greg Abbott Declares Statewide Disaster Over Screwworm Outbreak in Cattle

Gov. Greg Abbott declared a Texas disaster after New World screwworm was found in two calves, prompting cattle movement bans and a federal sterile‑fly eradication plan; ERCOT expects record power demand, the Secretary of State resigns, and groups seek to restore the Texas Dream Act.

2 sources. https://clstr.news/cluster/texas-gov-greg-abbott-declares-statewide-disaster-over-screwworm-outbreak-in-cattle

### 2026-06-09: USDA Leads Coordinated Fight Against New World Screwworm in Texas

USDA and Texas partners are executing a five‑prong plan and sterile‑insect releases to contain New World screwworm, following five U.S. cases including a new calf infection in La Salle County, Texas.

5 sources. https://clstr.news/cluster/usda-leads-coordinated-fight-against-new-world-screwworm-in-texas

### 2026-06-09: USDA bans all live animal exports to Mexico over screwworm outbreak

USDA halted all live animal exports to Mexico after screwworm cases were found in Texas and New Mexico, curbing West Texas feedlots while opening meat export chances for Mexican ranchers.

2 sources. https://clstr.news/cluster/usda-bans-all-live-animal-exports-to-mexico-over-screwworm-outbreak

### 2026-06-09: Screwworm infestations reported in Mexico and United States

Screwworm cases have been confirmed in a dog in Durango, Mexico, and in livestock and a dog in Texas and New Mexico, prompting quarantine zones and cross‑border health alerts.

2 sources. https://clstr.news/cluster/screwworm-infestations-reported-in-mexico-and-united-states

### 2026-06-09: US expands sterile‑fly program as New World screwworm resurges in Texas and New Mexico

USDA reports five New World screwworm cases in Texas and New Mexico and ramps up sterile‑fly releases, AI monitoring, and a trial of a genetically engineered male‑only strain.

2 sources. https://clstr.news/cluster/us-expands-sterilefly-program-as-new-world-screwworm-resurges-in-texas-and-new-mexico

### 2026-06-09: New World screwworm outbreak spreads across Mexico and the United States

USDA confirmed multiple New World screwworm cases in Texas and New Mexico, while Mexico reports over 2,000 active cases, prompting intensified sterile‑fly releases across both countries.

2 sources. https://clstr.news/cluster/us-and-mexico-report-new-screwworm-infestations-in-livestock

### 2026-06-09: US Halts Livestock Exports to Mexico Over Screwworm Outbreak

The US USDA has suspended all live animal exports to Mexico after detecting screwworm larvae in Texas and New Mexico, halting cattle, horses, sheep, goats, pigs and other species and risking supply disruptions

2 sources. https://clstr.news/cluster/us-halts-livestock-exports-to-mexico-over-screwworm-outbreak

### 2026-06-08: US USDA ramps up response to New World screwworm outbreak in Texas

USDA confirmed four screwworm cases in Texas and launched quarantines, sterile‑fly releases, and other measures as the parasite threatens livestock and could keep beef prices high.

8 sources. https://clstr.news/cluster/usda-ramps-up-response-to-screwworm-outbreak-in-texas

### 2026-06-08: Nuevo León records second human screwworm (myiasis) case

Mexico’s health ministry reports a second human screwworm case in Nuevo León, raising the state’s total to two as the country reaches 397 cases nationwide, with two deaths reported.

2 sources. https://clstr.news/cluster/nuevo-len-records-second-human-screwworm-myiasis-case

### 2026-06-08: Texas Deploys Sterile Flies to Counter New World Screwworm Threat

Texas officials, led by Gov. Greg Abbott, deploy sterile flies and activate emergency measures to combat a new New World screwworm outbreak in livestock.

6 sources. https://clstr.news/cluster/texas-deploys-sterile-flies-to-counter-new-world-screwworm-threat

---
Cite as: US-Mexico screwworm outbreak: containment and human impact. CLSTR, https://clstr.news/situations/rising-crossborder-pest-and-disease-outbreaks-spur-biosecurity-measures-in-mexico-and-the-united-sta