By Dr. Chris Rademacher and Dr. Justin Brown et.al
New World Screwworm (NWS) is a parasitic fly whose larvae (maggots) feed on living tissue. Unlike common maggots that feed on dead tissue or in decomposing organic matter, NWS larvae burrow into healthy flesh, causing severe pain, tissue damage, secondary infections, and potentially death if left untreated. NWS can affect livestock, wildlife, pets, and people.
NWS is not a food safety concern, and animals should be processed in accordance with USDA Food Safety Inspection Service (FSIS) or state regulations. Pigs previously infested with NWS that have been treated, are fully healed, and have met drug withdrawal times are safe to be harvested and enter the human food chain.
Now that a case has been diagnosed in cattle in Texas, State and Federal officials will direct the response in terms of the initial case and any quarantines and import restrictions following the strategies and actions outlined in the NWS Response Playbook.
For more information, review the Swine Health Information Center (SHIC) NWS factsheet or access screwworm resources from the USDA.
Why Should Swine Producers Be Concerned?
Even small wounds can attract NWS flies. Female flies lay eggs around wounds, and larvae hatch within hours and begin feeding on living tissue.
Common risk areas in swine:
- Piglet processing wounds
- Castration
- Tail docking
- Ear notching or tagging
- Needle teeth clipping
- Tattooing
- Injection sites
- Newborn piglet umbilical cords
- Fighting injuries and skin abrasions
- Shoulder sores
- Cuts from equipment, flooring, feeders, or waterers
- Tick or lice bites
- Farrowing-related wounds in sows
Source : iastate.edu