Do Usa Garden Snails Make You Sick?

Snails and slugs may not look dangerous, but they can kill if they carry a parasitic nematode (Angiostrongylus cantonensis) known as the rat lungworm.

Snails and slugs (secondary hosts) acquire the microscopic worm by feeding on the droppings of infected rats (the primary host) that in turn acquire the parasite when young by eating infected mollusks.

Other "transfer" hosts — including freshwater shrimp, land crabs and frogs — can also acquire the parasite in areas where rat lungworm occurs. When other animals such as dogs, horses and birds accidentally ingest the parasite, it attacks their central nervous system, and in humans it causes a rare and potentially fatal form of meningitis.

Exposure to rat lungworm may occur if you travel abroad or to certain areas of the U.S. The parasite is prevalent in Southeast Asia and tropical Pacific islands and Australia. It has also spread to parts of Africa and the Caribbean. In the U.S., scientists have found rat lungworm in Hawaii, the New Orleans area of Louisiana and, recently, in one aquatic and three terrestrial snail species in South Florida.

Rat lungworm is not known to occur in San Diego or the rest of California, but it could accidentally be brought here from an infested area on a plant harboring an infected snail or slug. Wholesale nurseries strive to exclude and eliminate all mollusks from the plants they grow, but they are not always successful. According to entomologist Tracy Ellis, the San Diego County Department of Agriculture had 42 interceptions of slugs and snails on shipments of incoming plant material from Hawaii and Florida during 2014.

Agriculture officials also worry about the plants brought here illegally by travelers that they don't inspect. Consider this the next time you travel and do your part to protect our communities from the rat lungworm and other exotic pests.

Individuals traveling to areas with rat lungworm should be careful what they eat. According to the U.S. Center for Disease Control and Prevention, risk factors include ingestion of raw or undercooked infected snails or slugs or pieces of snails or slugs accidentally chopped up in vegetable juices or salads or food contaminated by the slime of infected mollusks. It is possible that ingestion of raw or undercooked "transport" hosts such as freshwater shrimp can result in human infection, although this is less certain.

Contamination of the hands during the preparation of uncooked snails or slugs could also lead to ingestion of the parasite. People who handle snails or slugs while gardening should wash their hands thoroughly before eating or preparing food.

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