The state has confirmed two new cases of rat lungworm disease on Hawaii island, including in a toddler who was hospitalized and transferred to Oahu for care.

The potentially crippling illness has been most prevalent on the Big Island with five cases of rat lungworm, or angiostrongyliasis, in 2018. Seven cases have been confirmed statewide this year, including an Oahu toddler and an adult on Maui.

The toddler from East Hawaii became sick in October and was tested twice before health officials diagnosed the disease. The state Department of Health is investigating possible sources of infection.

In the second case an adult from West Hawaii was confirmed in August with a “mild case of rat lungworm” and has since recovered, according to the DOH, which was unable to identify the source of infection.

“We’re not sure why there’s so many cases on the Big Island, but we do know the semi-slug is found on the Big Island and it’s one of the most important vectors of the disease. With the rainy season in full swing, we may expect to see more slugs and snails around our homes and gardens,” said DOH Director Bruce Anderson.

The small semi-slugs, which range in size from 1 inch to as small as a grain of rice, can be hard to detect, Anderson said. “We can reduce the risk of rat lungworm disease by taking precautions to safely eliminate rats, slugs and snails in our communities. Keeping our young children away from these harmful vectors as well as thoroughly washing all produce before consuming it is crucial.”

Hawaii has seen just a “couple deaths” in the past 10 years, he said, but the illness can be debilitating in severe cases.

“There are likely lots of other cases occurring with less severe symptoms. It’s unknown how many of those cases exist,” Anderson said. “Undoubtedly, lots of people may experience headaches and other benign symptoms who recover and never know they were infected.”

Last year there were 18 confirmed cases of rat lungworm, most of them on the Big Island. The most common symptoms include severe headaches and stiffness in the neck, while the most serious cases can lead to neurological problems, severe pain and long-term disability.

The small but rising toll has been concerning enough for Gov. David Ige to commission a group to help prevent the spread of rat lungworm in the islands. The Joint Task Force on Rat Lungworm Disease has created a plan to train doctors statewide on detecting the disease. Many physicians in Hawaii are unaware of the symptoms and have delayed treatment for some patients as a result.

The first medical education course was in Hilo on Oct. 10, and the group is scheduling more sessions on Kauai, Maui and Oahu and on the Big Island for early next year, the DOH said.

“We’re seeing fewer cases so far this year, but again that doesn’t suggest there’s any less risk. The risks are still there, but the public’s understanding of the disease has been increased,” Anderson said, adding that the DOH also has included information about rat lungworm in food safety certification courses that food handlers in restaurants are required to complete.

“We have health educators holding presentations islandwide to inform residents of the risks and precautions that can be taken. The possibility of exterminating rats is unrealistic … I’m afraid this is a situation where everyone has to be doing their part. It requires constant vigilance and everyone’s help to keep rats under control.”