5 things you need to know about the invasive screwworm outbreak spreading panic.
- A flesh-eating threat is back: The New World screwworm, a parasitic fly larva that burrows into living tissue, has been confirmed in a major outbreak in Central America and is threatening to spread northward into the US and Mexico.
- It’s not a worm, it’s a maggot: Unlike common maggots that eat dead flesh, the screwworm larva attacks healthy, living animals—and occasionally humans—by creating deep, painful wounds that can be fatal if untreated.
- Livestock is ground zero: The outbreak is devastating cattle, sheep, and goats, causing massive economic losses. Infected animals develop oozing holes, require expensive treatment, and often die without immediate veterinary care.
- The sterile fly strategy is failing: The primary tool to stop screwworm—releasing sterile male flies to interrupt breeding—has been hampered by funding cuts and border disruptions, allowing the parasite to resurge in Costa Rica and Panama.
- A single bite can start an epidemic: Screwworm flies can travel 100 miles in a single season. A single infected animal crossing a border can launch a new outbreak, making containment a race against time for US and Mexican agriculture officials.