CDC Activates Emergency Response to New World Screwworm Outbreak in Texas and New Mexico

The Centers for Disease Control and Prevention (CDC) has activated a Level 3 emergency response to New World screwworm (NWS) infestations detected in animals in southern Texas and one New Mexico county, according to a June 11 announcement. This is the highest level in the CDC’s three-tiered emergency response framework, signaling a coordinated national effort to prevent human and animal health risks.

What is New World Screwworm?

New World screwworm is a parasitic fly species that lays eggs in wounds or body openings of mammals, including livestock, pets, and wildlife. The larvae feed on living tissue, causing severe infections. While primarily a threat to animals, human infestations are possible, though no cases have been reported in the U.S. as of June 2025, according to the CDC.

How is the CDC Responding?

The CDC is collaborating with the U.S. Department of Agriculture (USDA) and state health agencies to contain the outbreak. A USDA dashboard tracks animal cases, and a unified national strategy, led by the U.S. One Health Coordination Unit–New World Screwworm Interagency Working Group, includes surveillance, public education, and eradication efforts. This approach mirrors past successful campaigns that eliminated NWS from the U.S. in the 1950s and 1960s.

What Are the Risks to Humans?

The CDC emphasizes that human infestations remain extremely rare, with no confirmed cases in the U.S. However, individuals in affected areas are advised to monitor wounds and seek medical attention if symptoms like swelling, pain, or discharge occur. The risk is highest for those with open injuries or who work closely with animals, such as farmers or veterinarians.

Prevention and Public Health Measures

Healthcare providers in southern Texas and New Mexico are urged to report suspected NWS cases promptly. The CDC recommends keeping pets indoors, inspecting livestock for wounds, and using insecticides to reduce fly populations. The agency also highlights that NWS cannot spread between animals, animals and humans, or humans and humans.

Why This Outbreak Matters

The resurgence of NWS in the U.S. underscores the importance of cross-agency collaboration under the One Health framework, which addresses interconnected human, animal, and environmental health. Previous eradication efforts relied on sterile insect techniques and widespread surveillance, strategies that remain central to the current response. The CDC’s involvement reflects the potential for NWS to disrupt agriculture and public health if left unchecked.

For more information, visit the CDC’s New World Screwworm page cdc.gov/screwworm or the USDA’s outbreak dashboard screwworm.gov.