Unhealthy Eating

Vegetables are the epitome of healthy eating—unless they’ve been visited by snails harboring a painful parasite.

The parasite lives in the bodies, and possibly the trails, of slugs and snails.

Illustration by: Mike Austin

You shouldn’t fear your salad, but you may want to take a closer look at what’s in it before diving in—especially if it’s homegrown. And if you ever find yourself playing Fear Factor, it would be best to boil any slimy creepy-crawlies you might swallow.

A rare parasitic infection called rat lungworm disease is on the rise in Hawaii, and the primary suspects in its spread are slugs, snails and the backyard veggies on which they slink.

“It’s an emerging infectious disease,” says state epidemiologist Dr. Sarah Park. “It has been documented in Hawaii as far back as the 1960s, but it’s only been in the last 10 years that we’ve heard about a lot of cases.”

The rat lungworm parasite gets its common name from where it lives as an adult: in the lungs of rats. Larval rat lungworms venture into the wider world encased in rat droppings. When things go smoothly, a slug or snail eats the droppings, a rat eats the slug or snail, and the young parasites return home. Trouble occurs when a human ingests the infected slug or snail, or possibly their slime. The parasites die inside of their new host within weeks, but not before burrowing into the person’s central nervous system.

Many people infected with rat lungworm experience mild symptoms, such as muscle aches and sensitivity to light, or no symptoms at all. But full-blown cases involve eosinophilic meningitis, an infection of the fluid bathing the brain and spinal cord. Symptoms include excruciating headaches, a stiff neck, and tingling or ultra-sensitive skin. More extreme symptoms include paralysis of the legs, seizures and coma.

Forty-nine cases of eosinophilic meningitis attributed to rat lungworm have been reported in Hawaii since 2001. Nobody knows how many less severe cases have occurred. “I would not doubt that there are more cases out there than anybody is really aware of,” Park says.

The Big Island has been hardest hit, with 23 cases of eosinophilic meningitis reported since 2006, most in the rural Puna District. At least three Puna residents have been in comas, another is believed to have committed suicide because of the pain, and suspected new cases turn up regularly at the Puna Community Medical Center.

Homegrown leafy greens like lettuce and kale, with all those folds and crevices where tiny infected mollusks can hide, are the common denominator in most of the documented Big Island cases, Park says.

But carnivores beware: veggies aren’t always to blame.

“One guy and his buddies were drinking, and trying to one-up each other in terms of the grossest thing they could eat,”  Park says. “He grabbed one of these giant slugs and downed it, and sure enough—he came down with the symptoms.”

Park says research is needed to understand why rat lungworm is on the rise. In the meantime, there are simple precautions you can take to avoid the disease: If you’re growing produce, keep rats, slugs and snails in check. If you’re eating produce, thoroughly wash it and carefully inspect it first. And if you absolutely must eat a slug or snail (or lizard, frog, freshwater prawn, or flatworm, which can also be hosts) think boiled—not poke.