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Rat lungworm disease on Big Island gets more attention after Maui cases

Updated: 
April 30, 2017 - 12:05am

Editor’s note: This is the first part of a two-day series examining rat lungworm disease in Hawaii. Monday’s edition will look at whether cases are increasing and what research is being undertaken.

HILO — A disease long endemic to Puna has gained national attention after Maui residents and two tourists from the mainland have become ill.

Now, the state sends news releases about new cases of rat lungworm disease on the Big Island or Maui — a change in response from when primarily the Big Island had cases. On Friday, two more Big Island cases of rat lungworm disease were confirmed in the state, bringing the total up to 13.

Some ask why it took so long for the state to pay attention to a severe or even deadly ailment.

State Sen. Russell Ruderman, D-Puna, said “the fact that it’s spread to Maui, and some tourists, and got some national press has definitely raised its profile.”

“It’s too bad that it’s taken an outbreak on Maui for the state to take notice,” said Susan Jarvi, a professor in the Department of Pharmaceutical Sciences at the Daniel K. Inouye College of Pharmacy at the University of Hawaii at Hilo and a leading rat lungworm disease researcher.

State Rep. Joy San Buenaventura, D-Puna, said doctors in the state need continuing education about rat lungworm so they’ll more readily consider it as a possible diagnosis.

Patients routinely get turned away from clinics and ERs after being told their upset stomach, excruciating pain or other symptoms are from influenza, a sports injury or other problems.

But Dr. Jon Martell, medical director at Hilo Medical Center, said there’s “no commercially available, validated test that you can do for rat lungworm.”

Without exception, every patient with rat lungworm presents differently from others, he said. A patient with a severe headache, he said, might have a relatively mild case, while mild symptoms can worsen dramatically.

To verify rat lungworm, a spinal tap is needed. Asking to stick a needle in the back and remove fluid is “a lot to ask of patients,” Martell said.

“If we had a straightforward test, a lot of the issues would go away,” he said.

Hawaii Island and Maui have semi-slugs, the invasive species which Jarvi said is widespread, often teaming with nematode larvae and raising concerns about the need for more rat lungworm research.

Jarvi said every island in the state has slugs or snails infected with rat lungworm larvae.

“The semi-slug is a very, very effective intermediate host,” she said. It climbs high onto catchment tanks, low on lettuce and herbs, and seemingly everywhere in between.

The University of Hawaii at Manoa College of Tropical Agriculture and Human Resources reported in 2010 that since 1945, there had been fewer than 3,000 “documented” cases of rat lungworm worldwide, “with most of them occurring in Thailand and China.”

But to put the numbers in context and reassure tourists, the Hawaii Department of Health recently emphasized the number of visitors unaffected by rat lungworm.

“There were 8.7 million visitors to Hawaii in 2015, and our state had one case of rat lungworm reported in a nonresident in 2015, one case in a nonresident in 2016, and two nonresident cases in 2017,” Department of Health spokeswoman Janice Okubo said. “Most of the total cases, between one and 11 each year, have been residents.”

Charlene Chan, director of communications for the Hawaii Tourism Authority, said the group sent out a press release to state and global contacts to reassure tourists.

“We’re not aware of any impacts its had on bookings or traveling to the islands,” she said. “I think we still want to eat locally, don’t we?”

The best way to prevent getting the disease, according to the Department of Health, is “by taking food safety precautions — rinse and gently scrub all produce in potable (drinkable) water, inspect and properly store produce.”

A rat lungworm can produce thousands or tens of thousands of larvae, Jarvi said. UH-Manoa reported nematode larvae can infest people when they’re “about the size of the period at the end of this sentence.” That’s hard to see on a lettuce leaf.

Basic biology of the semi-slug, which seems to spread the parasites fastest and farthest, has not been extensively studied, Jarvi said.

The Hawaii Island Rat Lungworm Working Group has collaborated with five schools with school gardens. Instead of shutting the gardens down, Jarvi said, it’s better to teach kids. In Waimea, the students caught more than 3,000 snails.

“You teach the keiki; you have a whole generation of keiki that are going to grow up knowing this,” she said. “They could easily get infected at home, without this education.”

In the rat population, 90 percent have rat lungworm disease, Jarvi said. Among semi-slugs, about 70 percent carry rat lungworm.

How can you avoid the disease?

The Hawaii Department of Health says people shouldn’t be afraid of eating local produce. They just need to wash their food thoroughly no matter where it comes from.

However, Jarvi has more cautionary advice.

“People have to consider the possibility of cooking or freezing food,” Jarvi said. If you freeze vegetables that might contain the parasitic nematodes, do so for 24 hours, she said.

Martell said he treated a nurse from his hospital, a hotel worker from Waikoloa and restaurant worker from Hilo. All were “very careful and they still got the disease.”

Websites from the Centers for Disease Control and Prevention on down the line “will all tell you that this is a mild, self-limiting disease — and that’s wrong,” Martell said. “That’s wrong on so many levels, at least in East Hawaii.”

Rather, the disease can be quite severe and long-lasting.

“Something changed radically in about 2008,” Martell said. “We went from sporadic cases of relatively mild disease to multiple cases of severe, debilitating, catastrophic disease with arrival of semi-slugs.”

Severity of the disease rises with number of nematodes ingested by the human, he said.

The illness affects more than physical health.

“It is incredibly traumatizing to people once they understand they’ve got worms in their brain,” Martell said. “I can’t think of any way to soften that message.”

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

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