What is a screwworm? Information about the flesh-eating parasite

WASHINGTON (DC News Now) — The U.S. Department of Health and Human Services (DHHS) said a person in Maryland had the first human case of New World screwworm (NWS) in the United States after the person returned from El Salvador.

Put simply, NWS is a flesh-eating parasite. Although it normally does not occur or spread in the U.S., the attention the parasite and the case is receiving has many people looking for more information about it.

The Basics

The Centers for Disease Control and Prevention (CDC) explains that New World screwworm (NWS) infestation occurs when NWS fly larvae (Cochliomyia hominivorax) take over the tissue or flesh of warm-blooded animals. In places where the flies are present, people can become infested.

The CDC says screwworm flies are attracted to and lay eggs on and in open wounds. NWS typically does occur or spread in the U.S. The parasite usually is found in South America and the Caribbean. The CDC notes that people who travel to these areas, spend time among livestock animals, sleep outdoors, and have an open wound are at greater risk of becoming infested.

Symptoms

The CDC says that infestations are very painful. If you have one, you may see maggots (larvae) around or in an open wound. You also could have them in your nose, eyes, or mouth. If that should happen, CDC recommends telling your health care provider of any recent travel to Central or South America, or the Caribbean.

Here are additional symptoms:

• Unexplained skin lesions (wounds or sores) that do not heal
• Skin wounds or sores that worsen over time
• Painful skin wounds or sores
• Bleeding from open sores
• Feeling larvae movement within a skin wound or sore, nose, mouth, or eyes
• Seeing maggots around or in open sores
• A foul-smelling odor from the site of the infestation

The CDC noted that secondary bacterial infections sometimes occur and may cause fever or chills.