Weekly Screwworm Status Update_2026-June-23

The U.S. outbreak has continued to grow, but remains geographically concentrated. CDC’s June 23 update reports 16 domestically acquired U.S. animal cases as of June 22, with no locally acquired U.S. human cases. (CDC) Texas now reports 8 Texas counties with cases and 13 Texas premises with cases, up from 6 counties and 10 premises at our June 15 assessment. (Texas Animal Health Commission) New Mexico still reports one confirmed canine case in Lea County, now recovered/inactive. (Screwworm NM)

The most important new U.S. developments since June 15 are four additional confirmed Texas animal cases: one sheep/lamb in Crockett County, two cattle/calves in Edwards County, and one goat in Terrell County. The Terrell County goat was reportedly associated with a castration-site wound. (Farm Progress)

Newly confirmed U.S. animal cases since June 15

Current U.S. count: CDC reports 16 domestically acquired U.S. animal cases as of June 22. (CDC) Texas reports 8 counties with cases and 13 premises with cases. (Texas Animal Health Commission) New Mexico remains at one confirmed canine case in Lea County, now recovered/inactive. (Screwworm NM)

A minor discrepancy: Reuters reported on June 22 that three new Texas cases brought the U.S. total to 15; a later Farm Progress update and CDC’s June 23 page put the total at 16, apparently reflecting the additional Terrell County goat. (Reuters)

U.S. human cases

CDC’s June 23 situation summary says:

• No locally acquired U.S. human NWS cases have been reported.
• One prior travel-associated human case was confirmed in August 2025 in a person returning to the U.S. after travel to El Salvador.
• CDC continues to describe the current risk to the U.S. public and animals as very low, localized to areas where NWS cases have been reported. (CDC)

So the U.S. human status is unchanged from June 15: no confirmed locally acquired human cases.

Current U.S. case summary

Texas quarantine / infested-zone footprint: TAHC lists active quarantine in parts of Coke, Crockett, Edwards, Gillespie, Kerr, Kimble, La Salle, Pecos, Schleicher, Sutton, Terrell, Tom Green, Uvalde, Val Verde, Webb, and Zavala counties. Important: these are infested-zone/quarantine counties, not necessarily all confirmed-case counties. (Texas Animal Health Commission)

Mexico status and trend

The Mexico picture remains one of ongoing northward pressure with some possible reduction in total active cases, but the data are harder to extract cleanly from official dashboards than the U.S. data.

USDA’s current-status page says the Mexico map is updated Tuesdays and Thursdays at 5 p.m. ET, while detections within 100 miles are updated each business day. USDA also states that the sterile-insect release area/polygon is adjusted as needed “to maintain broad suppression and help prevent the pest from spreading to new areas.” (APHIS) USDA notes that SENASICA considers a case active at diagnosis and revisits it after 15 days to determine whether it should become inactive. (APHIS)

Supplemental reporting says Mexico had about 1,785 active cases, down by 136 from the previous report, but that cases within 100 miles of the U.S. border increased from 50 to 62 as of June 18. I would treat those as secondary-reporting figures until checked directly against the SENASICA/USDA dashboards before publication. (Farm Progress) Texas Tribune also reports nearly 28,000 detected cases in Mexico since November 2024, citing Mexican officials. (The Texas Tribune)

Interpretation: Mexico may be reducing some active-case burden overall, but the rise in near-border detections is the more important U.S.-risk signal.

Central America / Panama status

CDC reports that Central American countries and Mexico have reported more than 185,000 animal cases and 2,175 human cases in the current outbreak. (CDC) CDC also reiterates that the outbreak began in Panama and Costa Rica in 2023 and subsequently spread through Central America and Mexico. (CDC)

COPEG’s public page still appears less current than the U.S. pages. It displays data through epidemiological week 19, ending May 16, 2026, with 488 new cases, 66,061 cumulative cases since the start of the outbreak, and 34 weekly dispersal flights. It also says Panama had positive cases in all provinces except Guna Yala, and regional cases in Costa Rica, Nicaragua, Honduras, Guatemala, El Salvador, Belize, and Mexico. (COPEG)

COPEG’s visible page also states dispersal operations in Mexico and the United States, specifically Tapachula and Tuxtla, Mexico, but because the displayed statistics are over a month old, I would not use them as the current Central America count without checking COPEG’s most recent bulletin or dashboard manually. (COPEG)

USDA/APHIS control actions

USDA’s current-status page, last modified June 22, says APHIS maintains a dashboard of U.S. confirmed animal and wild-fly detections, capturing animal cases by county/state, animal type/species, confirmation date, and active/inactive status. It also tracks fly traps with at least one wild NWS fly detected. (APHIS)

Response actions include:

• Sterile fly releases in affected areas and adjusted release polygons in Mexico/U.S. border regions. (APHIS)
• Animal movement controls and surveillance. CDC describes USDA’s response strategy as including sterile flies, animal movement controls, surveillance, and outreach/education. (CDC)
• Expanded diagnostics capacity: APHIS deployed an NVSL entomologist to the USDA research lab in Kerrville and set up a mobile animal disease laboratory in Texas to allow faster initial confirmations. (Farm Progress)
• Large research investment: USDA announced about $105 million for 40 projects to strengthen detection, control, eradication tools, sterile-fly production, traps/lures, therapeutics, ecological modeling, wildlife surveillance, and response capacity. (APHIS)
• Pet-treatment support: FDA issued a June 11 EUA for generic nitenpyram tablets to treat NWS myiasis in dogs/cats meeting weight/age criteria; FDA notes this kills most larvae within hours but does not prevent reinfestation and does not replace veterinary wound care/removal of remaining larvae. (U.S. Food and Drug Administration)

Trade and movement restrictions

USDA says all southern ports of entry are currently closed to livestock trade. (APHIS) Texas movement controls remain significant: warm-blooded animals in a Texas infested zone may not move out without prior TAHC authorization, inspection, treatment documentation, and a movement certificate. (Texas Animal Health Commission)

New Mexico created a 12-mile infested zone around the Lea County dog case after confirmation, requiring inspection and treatment as needed prior to animal movement; the state also issued an emergency animal-health declaration on June 9. (Sierra County Government) New Mexico’s current status page says that dog has recovered and the case has transitioned from active to inactive. (Screwworm NM)

Practical implications

For veterinarians, the key issue is not just treatment but documentation and reporting. USDA is emphasizing confirmed detections only; Farm Progress quotes USDA saying many suspected reports are under investigation and that only confirmed detections are reported to avoid confusion and trade consequences. (Farm Progress)

For livestock owners, the practical message is daily wound surveillance. TAHC specifically recommends monitoring body openings such as the nose, ears, umbilicus, and genitalia, and watching for drainage, enlargement, maggots/larvae/eggs, and secondary infection. (Texas Animal Health Commission) The Terrell County goat case in a castration-site wound is a concrete reminder that ordinary management wounds are high-risk during active transmission. (Farm Progress)

For pet owners, national risk remains low, but pets in or recently exposed to affected areas should be checked for wounds. FDA’s nitenpyram EUA adds a treatment option for dogs and cats, but wound cleaning, larval removal, and veterinary care remain essential. (U.S. Food and Drug Administration)

For public health, the situation remains primarily veterinary/agricultural, not a U.S. human outbreak. CDC says no locally acquired U.S. human cases have been reported and that the current public risk is very low. (CDC)

For entomologists, the dashboard distinction between animal cases and wild-fly trap detections is important. If wild-fly detections increase, that would be stronger evidence of local reproductive activity than isolated animal cases alone. USDA’s dashboard explicitly tracks both categories. (APHIS)

What changed since June 15

1. U.S. count increased from roughly 12 to 16 domestically acquired animal cases by CDC’s June 23 update. (CDC)
2. Texas expanded from 6 counties/10 premises to 8 counties/13 premises with cases. (Texas Animal Health Commission)
3. New case counties include Crockett and Terrell, while Edwards had additional cattle/calf cases. (Farm Progress)
4. New sterile-fly dispersal flights were launched over newly impacted areas, including Crockett County; Edwards was already inside an affected area. (Farm Progress)
5. USDA announced $105 million for preparedness/response research and technology projects on June 16. (APHIS)
6. No U.S. human-status worsening: CDC still reports no locally acquired U.S. human cases. (CDC)

Uncertainties / discrepancies

The main discrepancy is 15 versus 16 U.S. cases. Reuters and some June 21–22 reporting gave 15 after the Crockett lamb and two Edwards calves. CDC’s June 23 update and Farm Progress’s June 23 report give 16, adding the Terrell County goat. For publication, I would use 16 as the current official public-health count, because CDC’s page is dated June 23 and references USDA APHIS. (Reuters)

The second uncertainty is the individual animal case list. USDA’s dashboard is the official location for individual animal cases, but its detailed rows are dynamic and not fully visible in the static text I could access. TAHC provides strong summary counts — 8 Texas counties and 13 premises — but not the full individual case table on the static page. (APHIS)

The third uncertainty is Mexico’s current active-case count. USDA points to SENASICA dashboards and says Mexico case maps/lists are updated frequently, but SENASICA’s official pages were not fully extractable in static text during this review. For your blog, I would manually check the USDA/SENASICA dashboards before publishing exact Mexico counts. Use the current secondary figures — 1,785 active cases and 62 within 100 miles of the U.S. border — only with clear attribution as supplemental reporting. (APHIS)

Map generated by ChatGPT using USDA, CDC, and state agency data. For full data sources, see the associated article.