Scientists continue to learn more about the potentially deadly parasite that causes rat lungworm disease. But much remains a mystery.
For years now, experts have known that Hawaii residents can, on rare occasions, become infected by the parasite Angiostrongylus cantonensis, which is found in other tropical locations around the world. The infection destroys parts of the brain and central nervous system, and symptoms can include fever, headaches, sensitivity to light, vertigo, blindness, bladder dysfunction, paralysis, comas and even death.
Puna currently represents the “epicenter for (rat lungworm disease) in the U.S.,” according to Susan Jarvi, a professor of pharmaceutical sciences at the University of Hawaii at Hilo College of Pharmacy.
The parasites live within rats, she said, which then pass them on to slugs and snails through their feces. Scientists believe that people become infected when they accidentally eat the snails or their slime trails left behind on produce.
Scientists say instances of the disease in Hawaii may have gotten a bump since the arrival of the invasive semi-slug around 2000. So-called because of the small shell on their backs, the semi-slug population has boomed, Jarvi said, and it can be found in many locations where other snails may not venture, such as on concrete.
However, Jarvi says, no substantial studies have yet been performed to find out the prevalence of rat lungworm disease on Hawaii Island, and there are currently no simple methods for diagnosing the infection in Hawaii.
Jarvi is partnering with Puna Community Medical Center and Clinical Labs of Hawaii, and is seeking help from volunteers in Puna as she endeavors to find a way to test for rat lungworm and to learn more about how it is being transmitted to humans.
Beginning at 8 a.m. Aug. 5, volunteers will be asked to answer questionnaires and donate small blood samples to be analyzed in Jarvi’s lab at the Daniel K. Inouye College of Pharmacy.
“Our goal initially was to test 500 volunteers,” she said. “That’s still sort of our goal. It might be coming in closer to 400. Right now we have about 250 samples in the freezer.”
Jarvi explained that one way to definitively identify a rat lungworm infection, also known as eosinophilic meningitis, is to collect a sample of a patient’s cerebrospinal fluid and search for DNA of the parasite. However, that’s a “pretty invasive” method, she said.
Instead, Jarvi is looking at ways of identifying markers in the blood that can point to the presence of Angiostrongylus cantonensis.
“I’m working with a lady from Thailand, a researcher who has developed a test strip that they use for diagnostics. What it does is it detects antibodies against the parasite,” she said.
In a Wednesday phone interview, state epidemiologist Dr. Sarah Park said that such a test could be highly beneficial, but warned that it’s a difficult undertaking.
“This isn’t an easy thing coming up with a diagnostic. It’s trying to understand what’s going on when there’s an infection and trying to figure out what’s the best kind of sample to detect, and how do we collect it?”
Park said that when the state Department of Health experimented such tests about a decade ago, the results were “hit or miss,” but added that if Jarvi’s work proves fruitful, “it would be great. It could be helpful.”
In addition to the blood tests, Jarvi’s study also will seek more information from people regarding how they prepare their fruits and vegetables, how they may have contracted the parasite, and how they were treated.
“It will help us get a better handle on what’s going on out here,” she said.
Email Colin M. Stewart at cstewart@hawaiitribune-herald.com.