What You Need To Know
Key Points or Updates
- NJDOH is providing this LINCS message and resources to inform healthcare providers and local health departments about New World screwworm (NWS).
- NWS is a fly that lays its eggs in open wounds or in other body cavities with mucus membranes, such as the nose, ears, eyes, or mouth. The eggs develop into parasitic larvae (maggots) that burrow into and feed on living flesh. The larvae are very destructive, causing extensive tissue damage, and infestations can be fatal. NWS primarily affects livestock, but the parasitic larvae can infest any warm-blooded animals, including humans.
- Symptoms of NWS myiasis include:
- Visible larvae or egg masses in a wound or body orifice with destruction of healthy tissue.
- Painful wounds, sensation of movement inside the wound, foul odor, bloody discharge, swelling.
- Patients may develop secondary bacterial infections or sepsis from NWS infestation.
- NWS is endemic in Cuba, Haiti, the Dominican Republic, and countries in South America. There is also a current outbreak of NWS in Central America and Mexico affecting both animals and humans. The fly that causes NWS myiasis has been steadily moving northwards from South America since 2023. As of September 2, 2025, the northernmost cases of NWS myiasis are located in southern Mexico.
- There is no immediate risk of infestation of NWS to people in the United States; however, travel-related cases have occurred in the past, including a recent travel-associated case in a Maryland resident who had returned from a country currently experiencing a NWS outbreak.
- CDC has resources for healthcare providers on their NWS website. There is also a scheduled project ECHO session on NWS on 9/15/2025 for physicians and healthcare providers — healthcare providers can register here.
Action Items
Healthcare Providers:
- Consider NWS in the differential for cases of myiasis in a person who has traveled to Mexico, Central America, or countries where the parasite is endemic.
- Immediately report suspect human NWS cases to the local health department where the patient resides. Local health department contact information can be found at www.localhealth.nj.gov. If you cannot reach the local health department, contact NJDOH Communicable Disease Service at 609-826-5964 during business hours or 609-392-2020 outside of business hours.
- Refer to CDC’s NWS recommendations for healthcare providers for information on diagnosis, specimen handling, disposal, and treatment for human NWS cases.
- Diagnosis is performed through CDC’s Diagnostic Parasitology Laboratory- NJDOH is available to assist healthcare providers in coordinating specimen submission to CDC.
- Ensure all larvae and eggs are properly disposed of according to recommendations. Do not dispose of any larvae or eggs in the trash or outside on the ground.
Contact Information:
- Darby McDermott, NJ State Public Health Veterinarian: Darby.McDermott@doh.nj.gov
- NJDOH Communicable Disease Service: 609-826-5964 during business hours or 609-392- 2020 outside of business hours
Resources:
CDC:
- About New World Screwworm Myiasis | Myiasis | CDC
- Clinical Overview of New World Screwworm Myiasis | Myiasis | CDC
- CDC Recommendations for Healthcare Providers
- Laboratory Diagnosis of New World Screwworm bench aid
USDA:
- New World screwworm — USDA
- New World screwworm: What You Need to Know (English and Spanish)
- New World screwworm Story Map
- Screwworm: An International Threat to Human and Animal Health