06/05/2026
A timely message from Dr. Rebecca Trout Fryxell ‼️
New World Screwworm (NWS) has been confirmed by USDA APHIS in the United States after being identified in the umbilical area of a calf in southern Texas. We are sharing this as an educational awareness update: this was a single calf, the calf has been treated, and no further cases have been identified. Rapid reporting and response are exactly what helps protect animal health and the livestock industry.
What to know:
- NWS is a parasitic fly; the larvae can infest wounds which include newborn navels, minor cuts, and summer injuries can be risk points—making routine checks especially important.
- If you see a wound that’s worsening quickly, has unusual irritation, or you suspect larvae, contact your veterinarian promptly and follow reporting guidance.
USDA has a response “playbook” and established procedures for detection, surveillance, and control. Playbook and additional guidance are available through USDA APHIS resources as well (www.screwworm.gov).
Tennessee producers should start practicing consistent warm-weather routines—more frequent health and welfare checks, prompt wound care, fly control, and prevention steps that reduce summer wounds/injury (fence and facility checks, castration/dehorning site monitoring, navel care, etc.). Awareness + good management + timely reporting keeps incidents small and contained.
Learn more about NWS via these factsheets:
USDA APHIS NWS myth busters factsheet:https://www.aphis.usda.gov/sites/default/files/nws-myth-busters.pdf
USDA APHIS NWS Playbook:https://www.aphis.usda.gov/sites/default/files/nws-response-playbook.pdf
UTIA NWS Factsheet:https://utia.tennessee.edu/publications/wp-content/uploads/sites/269/2025/08/W1338.pdf