New World Screwworm

The larvae (maggots) of the New World Screwworm Fly, Cochliomyia hominivorax, are obligate parasites of living flesh in warm-blooded animals, occasionally including humans.Female flies oviposit on or near pre-existing wounds or on mucous membranes inside the nose, mouth, and ears.Eggs hatch into larvae which burrow into the tissue and feed on the living flesh for approximately 7 days, after which they drop from the host and pupate.The adult screwworm fly emerges from the soil after 7 -54 days depending on temperature and humidity.NWS is endemic in South America, parts of southern Central America, and some Caribbean islands.NWS primarily infests animals; human cases are uncommon.However, human cases can occur among people who tend livestock in endemic areas, and in travelers to these regions, particularly among people with open wounds who sleep outdoors.Untreated infestations can result in severe tissue destruction and are potentially fatal. DIAGNOSTIC FEATURES OF THE THIRD-INSTAR LARVADistinguish C. hominivorax larvae from other species associated with incidental, facultative wound myiasis.Identify third-instar larvae to species level using a few key features shown below: