Cases of a rare brain parasite -- informally called rat lungworm disease -- are spreading in Hawaii, researchers and officials warn.

The state has confirmed nine cases of Angiostrongylus cantonensis, the formal name for the parasite.

Four are Maui residents, and three live on Hawaii Island, local media reports.

Additionally two visitors from California, newlyweds spending a lot of time recently in the state, contracted the disease.

"My symptoms started growing to feeling like somebody was taking a hot knife and just stabbing me in different parts of my body," said California woman Eliza Lape, 57.

The disease affects the brain and spinal cord, the CDC reports.

"I've had several operations, two pneumonias, a blood clot. Right now, I'm dealing with a kidney issue, all of which was spurred by the ratlung," said the California man, Ben Manilla, 64.

The disease is spreading at an apparently faster clip in 2017 than it has in years past. Hawaii officials say there were 11 reported cases in 2016.

"The cluster of cases, though not all confirmed, are very concerning," said Janice Okubo, spokeswoman for the Hawaii health department. "The recent cluster of cases this year on Maui suggests that something may have changed on Maui to increase the risk there."

But the Hawaii Health Information Corporation, an agency that compiles health care data, counted even more cases last year: 22.

To prevent contracting the disease, the Hawaii health department recommends against handling snails and slugs with bare hands. Additionally, for cooking purposes, snails, freshwater prawns, crabs and frogs should be boiled for at least three to five minutes.