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New World Screwworm

What is New World Screwworm?

New World Screwworms (NWS) are larvae or maggots of the NWS fly (Coch/iomyia hominivorax), that cause the painful condition NWS myiasis. NWS flies lay eggs in open wounds or orifices of live tissue. These eggs hatch into dangerous parasitic larvae, and the maggots burrow into flesh as they feed with sharp mouth hooks. The wound can become larger, and an infestation can often cause serious, deadly damage that can also be a site of secondary bacterial infection. NWS primarily infests livestock and wildlife but will infest any warm-blooded mammal, including humans. While rare, birds and reptiles can also be infested.

It is important to note this does not impact food and the food supply is safe.

 

New World Screwworm Photos

Images provided by USDA. Go to USDA Screwworm image gallery for more images.

sideview of new world screwworm
USDA
Closeup of three New World screwworm larvae (maggots).
Sohath Yusseff-Vanegas, USDA Agricultural Research Service
New World screwworm pupae are reddish brown in color.
COPEG

Prevention

  • Frequently inspect all livestock (cattle, sheep, goats, horses, swine, poultry, llamas, alpacas) pets, and captive wildlife for wounds
  • This includes navel wounds in newborns, dehorning/castration sites, tick bites, and any other open injuries
  • Be aware of the common signs of a NWS infestation including foul-smelling discharge from wounds, cream-colored larvae in wound tissue & unusual wound enlargement
  • Report any suspicious wounds or suspected cases of NWS immediately to your veterinarian, County Extension Agent or the ODAFF State Veterinarian at 405-522-6141

NWS in Wildlife

  • Monitor game cameras frequently for wildlife with cream-colored larvae in wound tissue & unusual wound enlargement
  • If detected, contact a game warden, veterinarian, or ODAFF with location, species, date and time seen. If pictures can be retrieved, submit to NWSinfo@ag.ok.gov with the above information
  • When intaking wildlife for rehabilitation, confirm location wildlife originated from. Examine for common signs for NWS infestation including foul-smelling discharge from wounds, cream-colored larvae in wound tissue & unusual wound enlargement
  • Report any suspicious wounds or suspected cases of NWS immediately to your veterinarian, local County Extension Agent, or the ODAFF State Veterinarian at 405-522-6141

What to Know Before Traveling to or Through an Infested State

  • Any species traveling from an infested state, but not an infested zone, can enter Oklahoma with a CVI that includes a statement "All animals in shipment do not originate from or transit through a NWS Infested Zone."
  • Any species that originates from an infested zone will need to meet the movement requirements for the state of origin AND obtain a permit from the Oklahoma State Veterinarian's office AND have a CVI that states "all animals listed were individually
    inspected and found free of wounds."

How to Test for NWS

Anyone who suspects NWS should contact their veterinarian, the Oklahoma State Veterinarian's office and/or their local OSU Extension agent. OSU Extension will have testing materials and can help get proper samples sent to the lab for testing.

Reporting New World Screwworm

All suspected and confirmed cases of NWS must be reported immediately to the State Veterinarian's Office at 405-522-6141 upon suspicion of clinical disease. Reports can be made by anyone, not just veterinarians or laboratories. Proper reporting will help slow the spread of this invasive pest. Do your part to help Oklahoma agriculture by reporting suspicious and positive cases.

Call State Veterinarian's Office

Go to NWS Report Form

 

 

Map of Confirmed Detections of New World Screwworm

Visit aphis.USDA.gov for more information about confirmed detections.