A deadly parasite, Raillietiella orientalis, is spreading rapidly through Florida’s snake populations, killing at least 19 native species and threatening ecosystems across the southeastern U.S. The lungworm, a whitish, worm-like organism, feeds on a snake’s lungs, causing inflammation, pneumonia, and sepsis. Snakes often die with the parasite protruding from their mouths, as described by researcher Jenna Palmisano, who found a dying dusky pygmy rattlesnake in central Florida.

The parasite originates from invasive Burmese pythons, which arrived in Florida in the 1990s. Burmese pythons, having co-evolved with the parasite in Asia, can tolerate infections. Florida’s native snakes, however, lack defenses against this foreign invader. Since its discovery in southern Florida in 2012, R. orientalis has spread northward, aided by Florida’s swampy landscapes and abundance of intermediate hosts like lizards and frogs, which transfer the parasite to snakes.

The parasite’s lifecycle is complex: cockroaches ingest infected snake feces, harboring larvae that are passed to lizards or mammals eaten by snakes. Inside the snakes, lungworms grow up to four inches, draining the host’s energy and often causing starvation. Florida’s pet trade exacerbates the spread, as wild-caught reptiles and amphibians may unknowingly carry the parasite.

Control efforts face significant challenges. Treating wild populations is impractical due to the parasite’s broad host range. However, preliminary research offers hope. Florida cottonmouths, though heavily infected, appear more resilient, suggesting some native snakes might adapt to the parasite over time, offering a glimmer of hope for conservationists.