New World Screwworm For Providers
New World screwworm (NWS) infestation is a type of myiasis that occurs when NWS maggots (larvae) feed on the living flesh of warm-blooded animals, especially livestock, but also including pets, wildlife, and humans. NWS flies are attracted to the odor of open wounds and mucous membranes, where they lay eggs. As the larvae feed, they cause painful wounds that rapidly grow larger and deeper. Secondary bacterial infections can also occur because of NWS infestations.
People at higher risk include those who live in or travel to areas with NWS flies and:
- Open sores or wounds, even small ones, or recent surgical sites.
- Medical conditions that can cause bleeding or open sores (like skin or sinus cancer).
- Spend a lot of time or sleep outdoors, especially during the daytime.
- Physically or mentally incapacitated and unable to keep flies away.
Consider NWS in patients with:
- Recent travel to regions where NWS is present.
- Visible larvae or egg masses in a wound, ears, eyes, nose, mouth, or other body orifice.
- Rapidly progressing and painful wounds with foul odor, bloody discharge, and swelling in otherwise healthy tissue.
- Sensation of movement in wounds or body orifices.
Report both animal and human infestations immediately to Alameda County Public Health Department 830am – 5pm (510)267-3250 and after hours and weekends to the On-Call Duty Officer at (925)422-7595.