First Human Case of Flesh-Eating Larvae Infection Confirmed: Maggots That Burrow Into the Body Can Be Fatal

Confirmed in Mexico near the U.S. border
Severe cases can lead to sepsis or death
U.S. authorities launch independent investigation

Cases of livestock infection by the parasitic fly larva known as the New World screw-worm (NWS), which eats the flesh of animals, have been reported in Mexico.

Parasitic Fly Larva

On October 6 (local time), Mexico's National Service for Agrifood Health, Safety and Quality (SENASICA) announced in a press release that a calf in Nuevo Le?n, a state bordering the United States, was confirmed to be infected with NWS, commonly referred to as the "New World screw-worm." The agency explained, "Thanks to control measures, the worm was already dead, and the other 84 animals transported together were not affected." Mexican authorities added that they are currently administering the antiparasitic drug ivermectin to animals 72 hours prior to transportation.

According to the website of the Animal and Plant Health Inspection Service (APHIS) under the U.S. Department of Agriculture, NWS has previously been found in the southern United States, Mexico, Caribbean island nations, and as far as Argentina in South America. The parasite lays eggs on livestock, pets, wild animals, and, rarely, on human wounds. The maggots that hatch from these eggs burrow into flesh, causing severe damage. The nickname "screw-worm" comes from the way the maggots bore into their hosts, similar to a screw being driven into wood. In the United States, the first human infection case was confirmed this August in a patient who had returned from a trip to El Salvador.

U.S. Secretary of Agriculture Brooke Rollins stated that this case appears unrelated to another incident reported in a different part of Nuevo Le?n two weeks prior, and announced, "We will deploy a field investigation team to independently verify the situation."

The New World screw-worm, known as the "flesh-eating maggot." Centers for Disease Control and Prevention website

Max Scott, a professor in the Department of Entomology and Plant Pathology at North Carolina State University, warned, "Once an infection begins, more flies are attracted and lay additional eggs. Depending on the location of the wound, maggots can invade vulnerable tissues such as the brain, or the wound may enlarge and lead to sepsis."

In the past, the U.S. government, in cooperation with Mexico and other countries, officially declared the eradication of this pest in the 1980s. However, in 2016, isolated cases were found in the U.S. mainland, including Florida. More recently, an elderly person in Chiapas, southern Mexico, was affected by NWS believed to have arrived via Panama. As a result, the Donald Trump administration decided in May to temporarily suspend imports of cattle, bison, horses, and other livestock from Mexico.