MAUI, HI (KHON) — Researchers are calling it an epidemic: a big spike in the number of people infected with rat lungworm disease in Hawaii.

The Department of Health says so far there are nine confirmed cases of the disease. Four are Maui residents, two are visitors who contracted it on Maui, and three live on Hawaii Island.

State officials are also looking into three possible cases on Maui, and one on Hawaii Island. The Department of Health adds 11 cases were confirmed on Hawaii Island in 2016.

Rat lungworm disease, a parasite officially known as Angiostrongylus cantonensis, affects the human brain and the spinal cord, according to the Centers for Disease Control and Prevention. The worm is carried by rats, then spread through snails or slugs that crawl onto fruits or vegetables.

University of Hawaii at Hilo researchers say rat lungworm disease is preventable, but only if people are informed. They’re asking for more funding from the state to let people know about the dangers, as well as to find out the most effective vegetable washes so people can continue to eat local and fresh produce safely.

According to professor Susan Jarvi, “that’s like the million-dollar question. Like, why do all of these cases originate on the east side of Hawaii?”

Jarvi says she was inspired to research rat lungworm disease after meeting fellow researcher Kay Howe, whose son, Graham, contracted the disease in 2008.

“He was in the hospital for four months, spent three months in a coma. He still has disabilities from this disease,” said Howe.

His disabilities include vision issues, low energy, short-term memory loss, and bladder and balance problems.READ MORE: Patient describes having rat lungworm disease: “The pain is just excruciating.”

Both researchers want to create a safety campaign on the dangers of eating raw fruits and vegetables that haven’t been properly washed.

They believe the rise in cases is due to a “semi-slug,” an invasive species that spread from Hawaii Island to Maui.

Both call it an epidemic.

“I’ve been using that term for a long time, but the Department of Health doesn’t see it that way,” said Jarvi. “I think now with all the new cases on Maui, and an increase in number of cases we saw in 2016 here on Big Island, I think it is an epidemic. I think we have real concerns about food safety.”

“Produce gets shipped all around the world. It is a global emerging disease. We don’t know if its range is going to expand,” adds Howe. “It’s not just Hawaii. We need to be mindful of that.”

Rat lungworm doesn’t just affect humans, it also affects dogs and horses, and can be fatal.