New World screwworm

Watch for NWS infestations in human patients. If you identify a suspected human case of NWS, email the CDC Parasite Diagnostic Laboratory at [email protected] and the One Health Epidemiology Team at the Utah Department of Health and Human Services at [email protected]. The email should specify that the inquiry pertains to a suspected human case of NWS infestation and include your name, phone number, and healthcare institution. You may also notify your local health department. Make sure to take high-quality photographs of the wound and larva; you might be asked to submit images for remote diagnosis.

Once photos have been taken, remove all visible larvae and eggs and place them in 70% alcohol. If instructed to submit larvae for identification, follow instructions for specimen handling and submission. Do not dispose of any larvae or eggs directly in the trash or on the ground. Rather, collect any remaining larvae and eggs in a separate leakproof container, submerge them in alcohol, place the container into a zip-top plastic bag, seal it, dispose of the sealed bag in the trash, and document this procedure in the medical record. After all larvae and eggs have been removed, provide appropriate wound care.

The best way to protect yourself from NWS is to stay away from NWS flies. However, if you are in areas in which NWS flies are present, try to prevent breaks in the skin, keep wounds clean and covered, wear long clothing, sleep indoors or covered with mosquito netting, and use EPA-registered insect repellant. Cover all wounds and seek medical attention if you think you might have an NWS infestation.

NWS was historically present in the United States but was eradicated in the 1960s after a concerted effort by the U.S. Department of Agriculture (USDA) using sterile insects. However, NWS has recently reemerged across Central America and Mexico, with animal and human infestations reported in every country in that region. In June 2026, NWS was detected in animals in Texas and New Mexico. Find the latest updates here.

The Utah Department of Agriculture and Food (UDAF), the Utah Division of Wildlife Resources (DWR), the Utah Department of Health and Human Services (DHHS), and Utah’s local health departments are prepared to collaboratively respond if an NWS infestation in an animal or person is reported in Utah. Rapid identification is critical for controlling NWS. Vigilance among community partners will facilitate effective surveillance. Those who should be alert for infestations among those at higher risk include healthcare providers, homeless service providers, immigration service agencies, organizations that provide resources for farmworkers and other outdoor workers, needle exchange program personnel, and county emergency managers.

If you know of an animal that might have an NWS infestation, fill out this form or email [email protected] to notify UDAF right away. If you have larvae from animals to submit for identification, see these larvae submission guidelines. For more information, visit the UDAF New World Screwworm webpage.