An over-the-counter medicine could give some hope to those who fear they’ve been exposed to rat lungworm disease via accidental ingestion of small slugs or snails.

Days after a Big Island family sued Island Naturals Market alleging its deli exposed them to the disease because of a slug found in a sandwich, Hilo Medical Center issued a public recommendation for people who find themselves in a similar scenario.

Dr. Jon Martell, the chief medical officer at Hilo Medical Center, says the recommendation is based on promising ongoing research from the University of Hawaii Hilo’s Rat Lungworm laboratory.

“If you see your child ingest a slug or find a slug in your sandwich, here’s something you can do right away on your own while you’re waiting to get care,” he said. “This is really for public awareness. It’s not something that we know from clinical studies that has significant benefit, it’s just something that’s very promising.”

Dr. Jon Martell
Hilo Medical Center Chief Medical Officer Dr. Jon Martell, right, accompanied by Dr. Doug Calvert, emergency department physician, is recommending an over-the-counter remedy for people who accidentally ingest an animal carrier of rat lungworm disease.     Courtesy: Hilo Medical Center

The rat lungworm parasite is carried by various animals, including prawns, crabs, frogs and rats, and can cause severe neurological damage and potentially fatal outcomes in humans. Scientifically known as Angiostrongylus cantonensis, it does not have a universal treatment and symptoms vary. The parasitic nematode got its name because it matures in the pulmonary arteries of rats. Humans most commonly become infected by accidental ingestion of parasitic carriers such as slugs or snails.

John Jacob RLW
Pharmacist John Jacob is researching whether or not anti-parasitic medicines can prevent rat lungworm disease. Tracey Niimi

When pharmacist John Jacob heard there was no approved protocol for treating rat lungworm disease in the U.S., he joined the laboratory to look into it more.

He is currently investigating the capability of nine common anti-parasitic medicines in preventing the disease as part of his research as he pursues a PhD in Pharmaceutical Sciences. The hope is these medicines can stop the parasite from entering the bloodstream and damaging the central nervous system.

“I said, ‘Hey, let’s test all of them and see what happens,’” Jacob said.

His first tests involved a common pinworm medication, also known as pyrantel pamoate, which is available under several brand names. It paralyzed nearly all the parasite’s larvae in petri dishes and more than 90% were dead within 30 days.

Jacob says it is possible, but not certain, that the medication could work in human stomachs to paralyze the parasitic larvae and then be flushed through the patient’s system before it spreads within the body and causes more damage.

“The next time you go to the bathroom it would go right through you,” Jacob said. “In theory that’s what’s supposed to happen.”

John Jacob examines parasitic larvae of Angiostrongylus cantonensis in the laboratory at UH Hilo to see if exposure to anti-parasitic medicine is able to kill or paralyze it. Courtesy: Hilo Medical Center

The unpublished study, entitled “In vitro efficacy of anthelmintic drugs on Angiostrongylus cantonensis L3 larvae,” is backed by researchers Jacob, Ingo Lange, Ghee Tan and Susan Jarvi. The lab is looking into other medications’ efficacy in killing the larvae outright, rather than simply immobilizing them.

The research developments come with a limitation. The laboratory will need to assess each medicine’s capabilities in lab rats before it can have full confidence that it will help humans.

Jacob has also studied the efficacy of using anti-worm medication albendazole, a drug that has been recommended in other countries to prevent the disease from developing. In the laboratory at UH Hilo, albendazole has successfully killed some of the parasite’s larvae, Jacob said.

Because there is yet to be an established medical treatment in the United States, the Hawaii Department of Health Task Force on Rat Lungworm Disease maintains its recommendation that patients seek immediate medical assistance.

Dr. Kenton Kramer, chair of the state task force and tropical medicine expert at the University of Hawaii John A. Burns School of Medicine, said the paralysis of the parasite’s larvae would only be temporary.

“Pyrantel may not work, but taken as directed should be safe,” he said. “Albendazole should be taken to kill the parasite in the brain before the parasite does any damage,” he said.

Last year, an Australian hospital recommended albendazole as a safe treatment for children who have swallowed a snail or slug. But the price for the drug can be prohibitive in the United States, running for about $200 a pill, compared to four or five cents in other countries.

Rat lungworm disease has received increased attention in recent years.

Several Hawaii lawsuits have been filed against eateries based on accidental consumption of slugs while eating leafy greens.

There were eight cases of rat lungworm disease on the Big Island in 2019, three of which occurred among visitors to Hawaii, according to the Department of Health.

While the cases are alarming, Martell says the disease is still relatively rare. Of the approximate 50,000 patients that circulate through Hilo Medical Center’s emergency department each year, about seven or eight cases are admitted for rat lungworm.

“It isn’t like we’re seeing it in high intensity,” Martell said. “It’s just that it can be devastating when we do see it.”

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