YOU GUYS — this isn't just a niche bug story; it's an actual public health threat resurfacing and the details are stomach-churning! The US Department of Agriculture has already confirmed five new cases, with four in Texas (two each in Zavala and La Salle Counties) and one dog that likely traveled through New Mexico from Mexico where they spread. If this isn't contained, CDC estimates suggest it could cost Texas cattle producers $732 million annually and hit the state economy by a staggering $1.8 billion because these screw-shaped larvae literally eat alive tissue. The fly is Cochliomyia hominivorax, and females can deposit up to 3000 eggs in any wound — small as a tick bite or larger openings like eyes and ears — with the larva feasting for about a week before falling out to pupate underground for 7–54 days into adult flies.
What's truly wild is that we already eliminated them here! The US Southwest was declared free in 1966, Mexico in 1991, and Panama in 2006 through the Sterile Fly Technique — bombing areas with irradiated male flies so they can never produce viable offspring. But around 2022, someone breached the Darién Gap barrier between Panama and Colombia and now the population is marching north again! The trail of destruction behind them includes Costa Rica (33 human cases, three fatalities), Nicaragua (two humans), and Honduras. Larvae need only one opening to invade: they'll take a tiny scratch, or lay eggs in eyes, noses, mouths, or even the rectum if available — which explains why these infestations are almost always found near body openings.
The clinical stories that follow get horrifying. One Costa Rican man had roughly 160 larvae pulling out from between his toes alongside two bacterial infections (Staphylococcus aureus and Pseudomonas aeruginosa) before he recovered with antibiotics. A Canadian tourist was extracted of another 30–40 in Costa Rica, only for doctors back home to pull at least 14 more from a shin ulcer formed later. But the worst-case scenario actually landed in Chicago — a girl who had a chronic scalp lesion woke up with an unrelenting headache and a large bump on her head; when they smothered it in ointment, roughly 45 larvae crawled out. Her MRI showed they hadn't penetrated her brain yet, because if they do, there is about an 8 percent mortality rate from intracranial infestation alone — so the fact she recovered at all means they were caught just before crossing the skull barrier!
Source: https://arstechnica.com/health/2026/06/screwworms-in-us-human-risk-is-low-but-they-can-burrow-through-your-skull
What's truly wild is that we already eliminated them here! The US Southwest was declared free in 1966, Mexico in 1991, and Panama in 2006 through the Sterile Fly Technique — bombing areas with irradiated male flies so they can never produce viable offspring. But around 2022, someone breached the Darién Gap barrier between Panama and Colombia and now the population is marching north again! The trail of destruction behind them includes Costa Rica (33 human cases, three fatalities), Nicaragua (two humans), and Honduras. Larvae need only one opening to invade: they'll take a tiny scratch, or lay eggs in eyes, noses, mouths, or even the rectum if available — which explains why these infestations are almost always found near body openings.
The clinical stories that follow get horrifying. One Costa Rican man had roughly 160 larvae pulling out from between his toes alongside two bacterial infections (Staphylococcus aureus and Pseudomonas aeruginosa) before he recovered with antibiotics. A Canadian tourist was extracted of another 30–40 in Costa Rica, only for doctors back home to pull at least 14 more from a shin ulcer formed later. But the worst-case scenario actually landed in Chicago — a girl who had a chronic scalp lesion woke up with an unrelenting headache and a large bump on her head; when they smothered it in ointment, roughly 45 larvae crawled out. Her MRI showed they hadn't penetrated her brain yet, because if they do, there is about an 8 percent mortality rate from intracranial infestation alone — so the fact she recovered at all means they were caught just before crossing the skull barrier!
Source: https://arstechnica.com/health/2026/06/screwworms-in-us-human-risk-is-low-but-they-can-burrow-through-your-skull