What is Angiostrongylus cantonensis (ann-gee-o-stronge-uh-luss can-tun-en-sis)?

It is a parasite, a worm, of rats. Infected rats pass immature forms of the worm in their feces. Snails and slugs get infected by eating infected rat feces. The young forms of the parasite mature in snails and slugs but do not become adult worms. The life cycle of the parasite comes full circle when rats eat infected snails or slugs and the immature parasites become adult worms.

Can people get infected with this parasite?

Yes. People can get infected, under unusual circumstances. However, even if infected, most people recover fully without treatment.

How can people get infected?

People can get infected by eating raw or undercooked snails or slugs that are infected with the parasite. In some cultures, snails are commonly eaten. Children have gotten infected by swallowing snails "on a dare." People can get infected by accident, by eating raw produce that contains a small snail or slug or part of one. We don't know if the slime left by infected snails and slugs can infect people (for example, if the slime gets on produce that is eaten). Other ways of getting infected might include eating raw or undercooked freshwater prawns, crabs, or frogs.

Can an infected person infect other people?

No.

Can people get infected by handling infected rats or rat feces?

No. The immature forms of the parasite passed in rat feces cannot infect people.

Can people get infected by handling infected snails or slugs - or only by eating them?

We don't know if the slime left by snails and slugs can infect people. (For example, if the slime gets onto hands and into the mouth or nose.)

Can giant African land snails be infected with this parasite?

Yes. This type of snail, which can grow larger than a person's hand, is just one of many types that can be infected. But snails can be infected only if they have eaten infected rat feces. We don't know if any of the giant African land snails in the continental United States are infected. These snails pose a major threat to agriculture because they multiple quickly and have ravenous appetites for plants and produce. It is illegal to own these snails without a special government permit.