Aug. 25 (UPI) -- The United States confirmed on Monday its first human diagnosis of the flesh-eating bacteria screwworm after its known eradication nearly 50 years ago and animal testing currently underway for future treatment.

U.S. health officials said its initial case of new world screwworm was detected after a person recently traveled to and returned from El Salvador in Central America bordering Mexico, according to the U.S. Department of Health and Human Services.

Screwworm's national designation arrived after Maryland's Department of Health and the U.S. Centers for Disease Control and Prevention first confirmed its existence on Aug. 4.

The New World Screwworm strikingly resembles a fly, and burrows when in larval stage into the flies of a living animal, such as livestock. The parasite infests warm-blooded animals and in rare cases humans, causing tissue damage and occasionally death.

The last U.S.-based case of screwworm was reported in August 1982 in the early years of the Ronald Reagan administration.