Hawaii rat lungworm cases differ from others around globe

  • Members of the Governor’s Task Force on Rat Lungworm Disease discuss with journalists what they learned shortly after speaking with health professionals.

    JEFF HANSEL/Tribune-Herald

The Governor’s Task Force on Rat Lungworm Disease says the problem is spreading, it’s become an “emerging” tropical disease and that unanswered questions need to be addressed with research.

“It’s very striking how severe (rat lungworm) is here in Hilo,” said Kenton Kramer, a task force member and associate professor in the Department of Tropical Medicine at the University of Hawaii at Manoa.


People who develop rat lungworm in Puna and Hilo typically get very sick, whereas people afflicted elsewhere on the planet usually are affected short-term and more mildly.

The task force was created by Gov. David Ige in 2016 to get independent input about the disease.

Members took time to meet with journalists this week in East Hawaii after returning recently from international travel seeking to learn how health providers in other countries treat the disease.

The task force attended Tuesday night’s Pahoa support group meeting for rat lungworm survivors. Members also visited an aquaponics farm that’s been struggling to prevent slugs from getting in.

They gained new recognition that the disease caused by the parasitic nematode Angiostrongylus cantonensis will need different treatment protocols in Hawaii than in other countries.

“All of the victims of rat lungworm disease should have a neurological consult early, and it’s looking like we should follow them over time,” said Dr. Vernon Ansdell, chairman of a task force subcommittee working to develop guidelines for diagnosis and treatment.

Task force members hope treatments can be developed for early intervention, but also for long-term disease. They’d like to see a blood test developed to identify rat lungworm, which would be much less traumatic for patients than current spinal taps.

Dr. Jon Martell, chief medical officer at Hilo Medical Center, said in November that the hospital had treated “21 highly suspected” cases of rat lungworm in the prior 12 months.

Martell has treated rat lungworm for about nine years, since he first started working at Hilo Medical Center as a hospitalist.

Since then, rat lungworm on Hawaii Island has increased in severity. Health providers hypothesize invasive “semi slugs” might be the reason.

Larvae infest humans when slugs or snails that ate rat droppings are accidentally eaten by people. Larvae mature and make their way to the human brain, causing neurological damage along the way.

“From the very beginning, it was clear to me that some level of research ought to be done using our patient population,” Martell said. Among patients treated in Hilo, versus treated elsewhere around the globe, there’s a greater prevalence of severe, long-lasting disease.

In Thailand, China, Brazil and elsewhere with rat lungworm, cases are mild and “self-limiting,” said William Gosnell, director of the Graduate Certificate in Tropical Medicine program at UH-Manoa. But in Hawaii, many patients experience severe illness, coma and even significant brain injury.

Rat lungworm larvae have been found in slugs and snails in Florida and Louisiana, and, according to the task force, there was a recent human case in Tennessee.

“It’s an emerging tropical disease. It’s spreading globally,” Kramer said. “We’re starting to see cases in travelers now, and I think people are going to be looking at Hawaii, and what’s being done here, for guidance.”

All five task force members who spoke with journalists this week said they would feel safe eating raw, well-washed locally grown produce, with the possible exception of kale. But they said more research is needed.

“There’s so many unanswered questions when it comes to rat lungworm,” Ansdell said.

Gosnell worried aloud about global warming and the possibility East Hawaii’s rat lungworm problem will spread as the range of infested snails grows on the mainland in the years ahead.


“This may be the harbinger of what you’re going to see in other places,” Gosnell said.

Email Jeff Hansel at jhansel@hawaiitribune-herald.com.