New World Screwworm

Coverage of New World screwworm detections, FDA treatment authorizations, and response efforts across animal health and agriculture as the parasite reemerges in the United States.

The affected animal is a 3-week-old calf in Zavala County, Texas. To date, APHIS has reported no further detections.

Zoetis' doramectin injection is now indicated for use in dairy cows, horses, sheep, swine, and deer to help mitigate NWS myiasis.

A US Environmental Protection Agency emergency exemption is allowing US officials to import Tanidil as part of a growing federal response to prevent New World screwworm from entering the country.

The authorization adds to a growing list of treatments cleared under emergency use as federal agencies ramp up efforts to prevent New World screwworm from reestablishing in the United States.

The FDA emergency use authorization (EUA) expands the New World screwworm treatment tool kit to cattle, small ruminants, horses, exotic mammals, and wild and pet birds.

The construction of a sterile fly production facility is underway at Moore Air Base in Edinburg, Texas, to help combat New World screwworm (NWS).

F10 Antiseptic Wound Spray with Insecticide received the EUA based on scientific evidence available.

The afoxolaner chewable tablet is the most recent drug to receive an EUA from the FDA to treat New World screwworm in feline and canine patients.

Once eradicated from the US in the 1960s, New World screwworm is again driving prevention efforts as cases move closer to the US-Mexico border.

In September 2025, the FDA issued a conditional approval for another drug indicated to prevent and treat New World screwworm (NWS) larval infestations in cattle.

Although the parasite has not yet been detected in the US, officials warn that its northward movement poses a serious risk to livestock and wildlife.

Credelio Quattro (Elanco) was previously approved by the FDA for treatment of infestation for 6 other parasites in dogs.

The product is also indicated treatment and control of cattle fever tick.

A concise Q&A for veterinarians summarizing the identification, reporting, treatment, prevention, and practical next steps as the New World screwworm approaches the US border.

The FDA determined that Credelio Cat may be effective in treating New World screwworm infestations in cats and kittens.

The program is used to combat New World screwworm, a global health threat.

The authorization is the first of its kind for dogs, as health officials track New World screwworm cases near the US-Mexico border.

Zoetis' Dectomax-CA1 is the first drug to receive conditional approval in the US for addressing this type of parasitic infestation.

The case is the closest the parasite has come to the US during the current outbreak.

The first human case detected in US, plus a summary of how the US is responding to New World screwworm.

The declaration allows emergency use of animal drugs not yet FDA approved for screwworm treatment.

The latest updates relating to animal care establishments and platforms.

This halt in imports is due to the rapid spread of the New World screwworm in Mexico, taking effect immediately.

The agreement also ensures ports remain open to livestock imports