Archive · 27 Sep 2025
Screwworm Detected Near US-Mexico Border
The New World screwworm, a dangerous parasite, has been found near the US-Mexico border.
It's like a tiny worm that burrows into the flesh of animals and people, causing wounds.
This parasite was once gone from the US, but now it's back, making officials concerned.
The worms are caused by flies that lay eggs in wounds.
Experts are working to stop the spread.
If you're in an area with screwworms, watch out for open sores and wounds that don't heal.
The USDA and other agencies are working to detect and eradicate the parasite.
New World screwworm detected in northern Mexico, near US border.
An 8-month-old cow in Nuevo León tested positive.
The parasite causes injury in livestock by laying eggs in wounds.
The U.S. eradicated the parasite in the 1960s.
Authorities are implementing a phased response strategy, including early detection and containment.
- Who
- The New World screwworm parasite
- What
- Detected in northern Mexico, near the US border, and causes serious injury in livestock and can infest birds and people.
- When
- The detection occurred recently, following eradication in the US in the 1960s.
- Where
- Northern Mexico, near the US border. A single case was detected in a person who traveled to the US from Guatemala.
- Why
- Screwworm larvae feed on living tissue, causing pain and potential death to the host.
- Parasite
- New World screwworm
- Location
- Northern Mexico, near the US border
- First Detection
- 8-month-old cow in Nuevo León
- Treatment
- Cow treated; other cattle given ivermectin
- US Detection
- One human case, traveled from Guatemala