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Officials rounded up giant African land snails in Miami-Dade County in September 2011. (Getty Images) Officials rounded up giant African land snails in Miami-Dade County in September 2011. (Getty Images)

Officials rounded up giant African land snails in Miami-Dade County in September 2011. (Getty Images)

Becky Bowers
By Becky Bowers November 3, 2011

Ag chief Adam Putnam says Florida's giant snail 'carries human meningitis'

Florida is now home to a slime-oozing plant-chowing snail the size of a teacup Chihuahua, and Adam Putnam wants to make sure that's temporary.

The giant African land snail can grow up to 8 inches, live nearly a decade, devour indiscriminately, lay 500 eggs at a time and snack on stucco for the calcium to build its shiny brown shell striped with cream.

It's a backyard horror and an agricultural nightmare.

Putnam, the state's agriculture commissioner, also says it carries disease.

The 1,000-snail invasion of a South Florida neighborhood became news in mid September. It's the biggest outbreak reported since the 1960s, when the state spent $1 million over the course of a decade battling three smuggled-in snails of a Miami boy that became 18,000.

Last weekend, CBS News Sunday Morning featured the snails along with other invasive species, from Illinois' Asian carp (fish) to Georgia's kudzu (plant). Southwest Miami homeowners described the "disgusting," "slithery," "juicy" pests. Putnam explained the public threat.

"With something like the snails we've got the trifecta," Putnam said. "It carries human meningitis, so people are concerned. It eats 500 different plants, so agriculture's concerned. And it eats houses, so homeowners are very concerned."

Leaf- and stucco-chomping? Check. Just ask the snails' Miami neighbors. But disease-carrying? PolitiFact Florida decided to check it out.

About that disease: Your brain and spinal column are protected by membranes called meninges. When they get inflamed, that's meningitis. Often there's a bacteria or virus that causes the swelling, but you might also hit your head, get cancer or take certain drugs and end up with the illness. Or get a fungus. Or a parasite.

Around the world, giant African land snails are known for carrying a parasite, one that spends part of its life in rats, that can cause a rare form of meningitis. (Most people fully recover without treatment.) It's known as the rat lungworm, or Angiostrongylus cantonensis. Snails — and prawns and crabs and frogs — pick up baby rat lungworms from rat droppings. Other animals who chow down on tasty raw crab or frog legs or snail guts pick up the larvae and can end up with the brain infection. Animals can also get it from eating unwashed snail-slimed greens, or from rubbing snail mucus into their eyes or noses or mouths.

That group includes humans.

Who eats giant snails? Plenty of folks, if not so many in the United States. Just consider escargot, the tasty French preparation of smaller, corn-fed snails doused in butter, garlic and herbs. Their meatier big brothers are an important protein source in coastal Nigeria. You can order them in a New York restaurant for $10. But it's not cooked snails that are the problem — for the same reason most folks don't eat raw shrimp or raw meat in general, for that matter. You heat them first, to kill uninvited disease-causing guests. It's the undercooked or raw ones that can be a problem. And also other exposure to slime.

Take two cases of meningitis in Louisiana: In one, an 11-year-old boy had eaten a small raw snail on a dare. In another, a 22-year-old had eaten two raw legs from a green tree frog — also on a dare.

(Note to America's youth: Don't do dares!)

Then there is Florida's infamous case of giant snail slime exposure last year, where an African holy man poured the stuff into mouths of followers hoping for healing. Instead, they got violently ill — though not of meningitis.

In England, giant African land snails are novelty pets that live in terrariums and sometimes crawl on their owners.

Where's the meningitis worry?

Snails that don't have a chance to pick up baby rat lungworms can't give them to you. Pet snails that haven't lived in the wild don't carry the parasite, which require rats to complete their life cycle. No parasite-incubating rats, no rat lungworms. No snail-caused meningitis.

The parasite is found in snails in the South Pacific, Asia, Australia and the Caribbean. It shows up in Hawaii and Puerto Rico, with sightings in Louisiana and Mississippi.

Florida had its rat lungworm scare in 2003, when a gibbon at Miami Metrozoo suddenly fell ill. It could have been a sign the rat lungworm had made it into the state's rats, snails, frogs and shrimp. Or it could have simply been infected monkey food from overseas. The Florida Department of Agriculture and Consumer Services dispatched a biologist, John Teem, to test snails around the zoo, said spokesman Sterling Ivey. He never found rat lungworm.

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He's tested some of the state's apple snails — an invasive species   — and hasn't found rat lungworm.

This year, when the Southwest Miami neighbors started to notice their garden snails seemed larger and more prolific than normal, Teem tested those, too. Even in the giant African land snails, he didn't find rat lungworm.

The state health department doesn't track meningitis caused by the parasite. Neither do the Centers for Disease Control and Prevention. It's exceedingly rare in the United States. Even in Hawaii, where the parasite's common, just five such cases in one year prompted academic study.

On Sunday, TV-watchers saw Putnam, the state's agricultural authority, warn them on national television about the snail's triple threat: house-eating, plant-devouring and disease-carrying. He didn't mention the disease hasn't been found in the state — and where it's been found in America, it's exceedingly rare. Or that to get it, you've got to eat a raw snail or get its mucus in your eyes or nose or eat unwashed snail-slimed produce.

Frequently, information sources point out that the giant African land snail can carry a meningitis-causing parasite. Putnam said, "We've got the trifecta," and said the snail "carries human meningitis." He leaves out some crucial details — most importantly, that the parasite that causes the disease hasn't yet been found in the state. And for that, we rate his statement Half True.

Our Sources

CBS News Sunday Morning, "The threat of invasive species," Oct. 30, 2011 (Video, quote at 7:42)

E-mail interview with Sterling Ivey, communications office, Florida Department of Agriculture and Consumer Services, Oct. 31-Nov. 2, 2011

E-mail interview with Jeffrey Dimond, public affairs specialist, Centers for Disease Control and Prevention, Oct. 31-Nov. 1

E-mail interview with Jessica Hammonds, press secretary, Florida Department of Health, Nov. 1-2, 2011

E-mail interview with Natasha Hochberg, assistant professor of epidemiology and medicine, Boston University Schools of Public Health and Medicine, Nov. 1, 2011

Florida Department of Agriculture and Consumer Services, "Florida Department of Agriculture and Consumer Services Identifies Giant African Land Snails in Miami-Dade County," Sept. 15, 2011

Miami Herald, "Giant snails invade Miami subdivision, spur local alert," Sept. 15, 2011

KGW NewsChannel 8, Portland, "Giant snails invade southern Florida," Sept. 17, 2011

ABC News, "Giant African snails invade Miami Florida," Sept. 16, 2011

U.S. Department of Agriculture's Animal and Plant Health Inspection Service, Pest Alert, April 2011

U.S. Department of Agriculture's Animal and Plant Health Inspection Service, Giant African snail, revised April 2011

Honolulu Zoo, African Land Snail, accessed Nov. 2, 2011

African Journal of Food, Agriculture, Nutrition and Development, "Nutritional and sensory profiling of the African giant land snail fed commercial-type and leaf-based diets in a rain-forest ecology," September 2011

Buka New York, Menu, accessed Nov. 2, 2011

Amateur Entomologists' Society, "Giant African Land Snail caresheet," accessed Oct. 31, 2011, Frequently Asked Questions, accessed Nov. 2 2011

U.S. Department of Agriculture's Animal and Plant Health Inspection Service, Finding of No Significant Impact, October 2011

U.S. Department of Agriculture's Animal and Plant Health Inspection Service, Environmental assessment, last modified Oct. 7, 2011

Centers for Disease Control and Prevention, Meningitis, accessed Nov. 2, 2011

Emerging Infections Diseases, Centers for Disease Control and Prevention, "Endemic Angiostrongyliasis, Rio de Janeiro, Brazil," July 2011

U.S. Department of Agriculture, "Not All Alien Invaders Are From Outer Space," accessed Oct. 31, 2011

Centers for Disease Control and Prevention, "Angiostrongylus cantonensis FAQs," updated Nov. 2, 2010

Illinois Department of Public Health, "Giant African snails prompt public health warning," May 6, 2004

Government of the Republic of Trinidad and Tobago, "Giant African snail advisory," Aug. 14, 2009

Louisiana Office of Public Health, "Eosinophilic Meningitis," accessed Nov. 1, 2011

Miami Herald, "Giant African snails smuggled into Florida for use in religious ritual, authorities say," March 11, 2010

Emerging Infections Diseases, Centers for Disease Control and Prevention, "Parastrongylus cantonensis in a Nonhuman Primate, Florida," December 2004

Emerging Infections Diseases, Centers for Disease Control and Prevention, "Full Recovery from Baylisascaris procyonis Eosinophilic Meningitis," June 2007

Oxford Journals, Clinical Infectious Diseases, "Eosinophilic Meningitis due to Angiostrongylus and Gnathostoma Species," 2009

American Journal of Tropical Medicine and Hygiene, "Eosinophilic Meningitis Attributable to Angiostrongylus cantonensis Infection in Hawaii: Clinical Characteristics and Potential Exposures," 2011

Snail Busters blog, About, accessed Nov. 2, 2011

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Ag chief Adam Putnam says Florida's giant snail 'carries human meningitis'

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