The federal government is working with local, state & tribal agencies in a unified response to the spread of New World screwworm scientifically known as Cochliomyia hominvorax. Since the 1960s screwworm has mostly been eradicated in Northern America due to strong protective measures taken.

NWS for short is a type of fly that lays larvae on warm blooded creatures. The larvae burrow into tissue and feed for seven days. Once the larvae is done feeding they retreat to the ground where the cycle begins happening for them to mature and spread more eggs. The average female screwworm fly can lay between 200-300 eggs each time and possibly live for up to thirty days.

In South America outbreaks are common and as well as other parts of the world in the western hemisphere where strong insect control is not prevalent. In the past decade screwworm has gradually made its way further north now reaching the United States.

As of this writing there are import restrictions issued by the USDA on 22 regions across the world some tightly linked to screwworm. With so many restrictions evidence shows multiple outbreaks not only related to the NWS. On June 11th the FDA issued emergency use authorization for over the counter medication treating dogs and cats.

“The U.S. government is maintaining an aggressive approach to stop the spread and eradicate this pest,” said U.S. Health and Human Services Secretary Robert F. Kennedy Jr. “When I signed the initial emergency declaration back in August 2025, we established a proactive defense. Today’s authorization is the latest tactical tool in that ongoing containment strategy — providing an affordable, fast-acting treatment for dogs and cats in affected areas.”

Texas has been hit the hardest so far in the United States.

The first reported case of New World Screwworm in the United States occurred June 3, 2026. Source: USDA

On June 8th the first reported case in a dog happened near Lea County, New Mexico. The case was linked to a household dog and not a stray animal.

“This situation is evolving, and we expect new information to emerge as our investigation continues. USDA is committed to sharing what we learn quickly, accurately, and transparently so animal owners and local communities have the information they need to stay vigilant,” said Dudley Hoskins, Under Secretary for Marketing and Regulatory Programs. “We are working closely with our partners in New Mexico, Texas, and across the region to ensure we identify, contain, and respond to any potential cases as swiftly as possible.” 

The government currently has a five pronged approach to the screwworm outbreak:

Currently there has been no reported cases in a human.

This story is ongoing and will be updated