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Tiny worm vs. giant snail: Parasitic nematodes pose real threat to snails in Florida

Not only are invasive species able to wreak havoc on local ecosystems, but they sometimes play host to dangerous parasites as well. So is the case with the giant African snails of South Florida, which are known to carry a tiny roundworm parasite that can infect humans, dogs, horses, birds, and other animals. Now experts are warning residents that the parasitic worms are present in at least three other non-native snail species currently living in the region.

The parasitic worms, Angiostrongylus cantonensis, more commonly known as rat lungworms, are members of the phylum Nematoda consisting of around a million species, over half of which are parasitic. Several species of snails serve as intermediate hosts; the worm larvae live in the snail guts until infective. The worms infect larger animals that prey on the snails. Humans are incidental hosts, usually picking up the worms from eating raw or undercooked snails or inadequately washed produce.

The giant African snail, Achatina achatina, grows large enough to fill an adult human hand. It is one of several non-native, invasive snail species residing in South Florida. Researchers have known for some time that these snails carry rat lungworms, and they have been testing snails throughout the state to determine how far the parasite has spread. The worms were recently detected in three other snail species, all of which are also non-native intruders.

“Determining the geographic distribution of this parasite in Florida is important, due to the hazards to human health,” said Heather Walden, an assistant professor of parasitology in the University of Florida’s college of veterinary medicine.

The parasite can cause a fatal form of meningitis in people who become infected from eating raw or undercooked snails. It has been widely recognized as a public health problem in large parts of Asian and Hawaii.

“Humans can’t become infected with this parasite unless they eat an undercooked or raw snail,” says Walden, lead author of a

About John Tyburski (97 Articles)
Former staff writer for Science Recorder.