The New World Screwworm is one of those creatures that seems like it comes from a horror show. It's not actually a worm - it's the larval stage of a fly that lays eggs in open wounds on warm-blooded animals, particularly cattle; the eggs hatch into masses of flesh-eating maggots. The story gets even worse, but some of you may be eating. You've been warned.
New World screwworm (NWS), or Cochliomyia hominivorax, is species of parasitic fly that completes part of its lifecycle by feeding on the tissue or flesh of warm-blooded animals and people. NWS flies are attracted to wounds and body openings like the nose, eyes, ears, and mouth, where they lay eggs. The eggs hatch into maggots (larvae) that eat live tissue, causing a worsening, often painful and foul-smelling wound.
They used to be common in the United States, especially in the South and on the Southern Plains.
If it's news to you, a) you're lucky, and b) that's thanks to a government effort that eradicated the parasite from North and Central America over sixty years ago in a fairly amazing bit of applied biology:
Max Scott, an entomology and plant pathologist who has genetically modified screwworm so the flies don’t reproduce, said outbreaks are typically controlled by rearing flies in a factory and sterilizing the bugs by exposing them to gamma rays when they are at the pupal stage. Scientists then release enough sterile flies to overwhelm the local fertile fly population. When the fertile female mates with a sterile male, they don’t produce offspring.
The program to sterilize billions of male screwworm flies began after World War II (great audio history of the program here) and gradually pushed the insect back across the Isthmus of Panama - the narrow strip of land connecting South and Central America. There - the narrowest point of land between the Arctic Circle and Tierra del Fuego - a variety of authorities have kept a steady barrage of sterilized males in production, preventing the movement of the species back to the north.
Until now:
The USDA says its National Veterinary Services Laboratories in Ames, Iowa, tested a sample from the case in a 3-week-old calf in La Pryor, Texas, and confirmed Wednesday that it was New World screwworm. The agency has activated personnel on the ground in Texas to contain and eradicate the parasite, including a 20-kilometer infested zone and implementation of quarantines, movement controls and surveillance in the area. It’s also expediting targeted release of sterile flies, which are used to overwhelm fertile flies in the area to limit spread.
The problem is that the infrastructure to produce the sterile files - breeding them by the hundreds of millions in large rooms, loading them onto airplanes, and dropping them across infested areas - pretty much died out in the US decades ago, as the plague was pushed back to Colombia. The few facilities that remain are in southern Central America, where the flies were actually needed.
So - why the sudden comeback?
The lefty media says it's because of Trump administration's cuts to foreign aid.
But there juuuust might be another reason (emphasis added):
NWS infestations (presence of maggots on or in the body) do not regularly occur in the United States, but cases have occurred in travelers returning from areas where flies are present. If you travel to these areas, have an open wound and spend a lot of time outdoors, you may be at greater risk of becoming infested with NWS.
So, can you think of a few million people who "returned from" areas where the flies are present, and spent lots of time outdoors, perhaps in the form of huge caravans forming south of the Isthmus of Panama and marching inexorably northward, over the past six years or so?
