What to know
- Currently, the New World screwworm (NWS) fly is not present in the United States and there are no cases of NWS in the United States.
- Recently, countries in Central America and Mexico have been experiencing an outbreak of NWS.
- In the outbreak region, NWS is primarily infesting livestock, wildlife, and pets. However, there are also cases of NWS in people.
- Infestations by NWS maggots can cause painful and foul-smelling wounds. If not caught early and treated, it can lead to extensive tissue damage, and potentially death.
Current situation
In 2023, Panama and Costa Rica identified an outbreak of NWS. Since that time, all countries in Central America and Mexico, where NWS was previously controlled, have identified cases in animals and people.
Cases of NWS in Central America and Mexico
There has been one confirmed case of NWS in a person who returned to the United States after traveling to El Salvador. Currently, the NWS fly has not been detected in the United States and there is no immediate risk of infestation to people.
CDC is closely following this outbreak and is working with the U.S. Department of Agriculture (USDA) and other federal and state, local, and tribal partners to prevent further spread of NWS among people and animals. The strategy to respond to and control the NWS outbreak, led by USDA and in coordination with other federal agencies, includes the release of sterile flies, animal movement controls and surveillance, and outreach and education in affected areas.
What you should do
In areas where the NWS flies are present, the best way to protect yourself from infestation is to
- Keep open wounds clean and covered, no matter how small or location on the body.
- Wear loose-fitting, long-sleeved shirts and pants, socks, and hats to limit exposed skin.
- Treat clothing and gear with products containing 0.5% permethrin.
- Sleep indoors or in rooms with screens.
Watch for symptoms
If you see or feel maggots (larvae) in or on a wound or other area of your body, contact your healthcare provider immediately. They will need to remove all of the maggots, sometimes through surgery. Do not try to remove or dispose of the maggots yourself.
Symptoms can include
- Unexplained, painful wounds or sores that do not heal.
- A foul-smelling odor or bleeding from the site of the infestation.
- Seeing maggots or feeling movement in open wounds or sore or in the areas of the body such as the nose, mouth, eyes, ears, or genitals.
Report suspected cases
If you are a healthcare provider and you suspect a patient has an NWS infestation, report it immediately to your local or state health department. Veterinarians should report any suspicious animal cases immediately to their state animal health official and APHIS office.