APR 16, 2017 10:08 AM PDT

Brain Parasite Makes for a Terrible Hawaiian Souvenir

WRITTEN BY: Xuan Pham

Travelers heading to the beautiful Hawaiian paradise should be warned to avoid raw snails and slugs. Hawaiian state officials have confirmed nine cases of rare brain parasitic infections caused by the rat lungworm found in these gastropods.

In the past three months, officials identified nine total cases of rat lungworm disease: three patients were from the Big Island, four were Maui residents, and two mainland travelers who also visited Maui. "Of the nine confirmed, eight have required hospitalization," said Dr. Sarah Park, Hawaii’s state epidemiologist, and chief of the Disease Outbreak Control Division in the Department of Health. "There have been no deaths."

The rat lungworm (Angiostrongylus cantonensis) is so named because the parasite matures in the pulmonary arteries of rats. But the feces of infected rats can transmit the parasite to garden-variety slugs and snails, which become the parasite’s intermediate hosts. When humans consume these infected gastropods, either accidentally or on purpose, the parasite hitches a ride to the brain and spinal cord.

"What happens is that the parasite gets into humans -- humans are not the host that it can complete its life cycle in, as opposed to being in a rat -- so when it gets in a human, it can get lost, and it will go to the brain, and it'll stay there," said Heather Walden, an assistant professor in the department of infectious diseases and pathology at the University of Florida. "When it gets to the brain, you can have eosinophilic meningitis.” Meningitis is inflammation and swelling of the meninges.

"Angiostrongylus cantonensis can present differently in adults and children. So usually, in adults, one of the main things that you hear complaint of is a headache,” said Walden. "In children, it's more the nausea and vomiting, not so much the headache."

In the best-case scenario, infected patients have zero or very mild symptoms that resolve in a few weeks. In the worst-case scenario, infection can lead to coma or even death. For the two mainland visitors who were infected on their honeymoon to Maui, they’ve been unlucky and have suffered other serious complications associated with the rat lungworm infection.

The parasite is endemic in Hawaii as well as in other parts of the continental US, including California, areas along the Gulf Coast, and even Oklahoma.

To avoid brain encounters with the rat lungworm, experts obviously recommend against consuming live or raw snails and slugs. In addition, they also urge people to carefully prepare lettuce and other produce, as these may hide a snail or two. It’s also worth noting that the infection isn’t contagious from person to person. Just mind what you eat. And finally, humans make terrible hosts for the parasite and these worms will eventually die out in our system.

Additional sources: CNN

About the Author
Doctorate (PhD)
I am a human geneticist, passionate about telling stories to make science more engaging and approachable. Find more of my writing at the Hopkins BioMedical Odyssey blog and at TheGeneTwist.com.
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