6 Things You Need to Know About Rat Lungworm Disease Before You Eat a Salad

Everyone’s talking about the recent disease outbreak affecting the Hawai‘i. Find out what it is, where it comes from and how you can prevent it.
Rat lungworm Disease

Photo: Hawai‘i Department of Health and Centers for Disease Control and Prevention


A recent outbreak of a rare disease caused by a parasitic worm that invades the brain and spinal cord on Maui has raised concern and even fear about what we’re putting into our mouths. And rightfully so.


Here’s what you need to know about rat lungworm, or angiostrongyliasis.


SEE ALSO: 15 Ways to Protect Your Family from Rat Lungworm Disease in Hawai‘i


1. It’s More Common Than You Think

Even though the Hawai‘i Department of Health calls rat lungworm a rare illness, with between one to nine cases reported every year and two deaths since 2007, it’s hard to tell just how many people get infected. Symptoms can range from very mild—headaches, stiffness of the neck, nausea—to severe, even resulting in temporary paralysis or comas. And symptoms usually start one to three weeks after exposure and can last from two weeks to months. Because of this, the disease can go undetected or unreported. This year, six cases have been confirmed on Maui, with three more under investigation. But Susan Jarvi, a professor of pharmaceutical sciences at UH Hilo, says she’s been researching this disease for more than five years, talking with farmers and residents on the Big Island about what it is and how to prevent it. She’s been getting a couple of calls a week about it, even before the recent Maui outbreak. “On the Big Island, practically everybody knows somebody with rat lungworm disease,” she says. “It’s been going on so long … It’s a fairly preventable disease, if you know about it.”


Rat lungworm disease

Photo: Hawai‘i Department of Health and Centers for Disease Control and Prevention


2. It’s Everywhere

People on every Hawaiian island—not just Maui or the Big Island—are at risk, thanks to our tropical climate. The disease is caused by a parasitic nematode, the adult form of which is found in rats. They host the worm and pass the larvae through their feces, which slugs—particularly the invasive semi-slug—and snails feed on. Humans get infected by consuming raw produce—leafy greens, herbs, sweet potatoes—or water contaminated by the slug or snail. You can also get sick by eating raw or undercooked snails, slugs, prawns and freshwater crabs. The DOH says it’s not known for sure if eating the slime left by infected slugs and snails causes any infection, but who wants to risk that?


3. There’s No Cure

The parasites die over time, so the infection is self-limiting. And, since symptoms vary so much—from headaches to vomiting to paralysis—there’s no specific treatment or medication for this disease. (Rat lungworm is hard to diagnose, too. The most effective method, so far, has been to get a sample of the cerebral spinal fluid from the infected person and run a molecular test on it. Jarvi is working on a way to detect the disease through a simple blood sample.) Anyone who has symptoms should see a health-care provider as soon as possible.


4. Beware of Uncooked Vegetables

There’s a reason why other countries, particularly those in humid, tropical climates, cook everything, including veggies. Heating them to at least 165 degrees—and freezing, too, for more than 48 hours—kills most bacteria and parasites, including rat lungworm. If you’re going to eat raw veggies, make sure they’ve been cleaned thoroughly. That may be hard to do in a restaurant, where you’re served a dish that’s been prepared out of your sight.


Rat lungworm disease

Photo: Hawai‘i Department of Health and Centers for Disease Control and Prevention


SEE ALSO: Rat Lungworm 101: What You Need to Know About This Potentially Deadly Parasite


5. It Can Be Prevented

Aside from avoiding all fruits, vegetables, slugs, snails, frogs, shrimp and prawns, there are easy ways to prevent contracting rat lungworm disease. First, wash all produce—even fruits—especially if you’re going to eat them raw. Since tiny snails and slugs are harder to detect on leafy greens, each leaf should be carefully washed, front and back, in water. (No need to add salt, bleach, vinegar or other cleaners.) Mikala Minn of Mahele Farm, a 10-acre community farm in Hāna, says you have to wash fruits and vegetables under running water, not just soak them in a bowl of water. He even recommends peeling bananas from the closed end and not eating any part of the fruit that was exposed. “Slugs are all over bananas,” he says.


If you have a garden at home, it’s important to controls rats, slugs and snails. Minn says the most effective way for his staff to deal with slugs is by hand-picking them and putting them in a concentrated salt solution. “That decreased the population [on the farm] by 50 percent,” he says.


6. Don’t Be Afraid To Buy Local

This recent uptick in rat lungworm cases has already impacted local growers. Mahele Farm, which also manages school gardens in Hāna, has decided to keep students out of the gardens for the rest of the year. Minn has also noticed fewer residents coming to the community farm—and even fewer taking lettuce. Tish Uyehara of Armstrong Produce, the largest wholesale produce company in the state, says some hotel restaurants are already requesting produce from the Mainland, where rat lungworm disease hasn’t been a problem. But don’t worry: It’s OK to purchase locally grown fruits and vegetables; just be sure to inspect and wash them thoroughly before eating them.