During 2005–2008, more than 1 billion live animals were legally imported into the United States for food or pet trade markets. One such animal, the swamp eel, can carry parasites (worms) called gnathostomes.

If those eels are eaten undercooked or raw, this parasite can cause mild to serious (blindness, paralysis, and even death) consequences. This parasite is native to Southeast Asia but not to the United States.

Rebecca A. Cole, PhD, Parasitologist with the US Geological Survey's National Wildlife Health Center discusses a study concerning Gnathostomes in Asian swamp eels here in the US in this 2014 interview.