State Department of Health officials confirmed two more cases of the parasitic disease rat lungworm today and said another four are probable.

The new reports stem from a single incident in Keaau on Hawaii island where six state residents drank kava, which is made from the piper methysticum plant and is used to promote relaxation. After downing the homemade brew, which had been sitting outside all night, they discovered slugs at the bottom of the large bowl.

The six adults were hospitalized and their illnesses reported to the department over the weekend, said health officials, who announced the new cases at a news conference this afternoon at the department’s headquarters on Punchbowl Street. The two patients with confirmed rat lungworm disease are Big Island residents, while three of the possible cases also involve Big Island residents and one is a Maui resident.

“The department is continuing to monitor this serious illness spread to individuals by infected slugs and snails,” said Dr. Virginia Pressler, the state health director. “Cases like this recent cluster are especially concerning because they can be prevented with basic precautions such as storing food in covered containers and properly inspecting and washing food before eating. These healthy habits can protect against food contamination and prevent serious illnesses.”

Officials said the two confirmed cases bring this year’s total of rat lungworm to 11 confirmed cases in Hawaii, which is already more than the rat lungworm average for an entire year for the state. Although rat lungworm has been endemic to Hawaii for 50 years, the state normally averages nine cases in any 12-month period.

The incident brings the count of confirmed cases on the Big Island to five in the last three months. There have been six confirmed cases on Maui. All but two of the cases involved residents. The other two cases — California newlyweds who contracted rat lungworm disease after visiting Hana in January — recently generated nationwide negative publicity for the state’s visitor industry.

Rat lungworm is typically prevalent in Southeast Asia and the Pacific islands. Victims most often contact the disease by consuming produce that contains a raw or under-cooked slug or snail that has been infected with the Angiostrongylus cantonensis parasite, which was carried to Hawaii by rats. The adult parasite is only found in rodents. But snails, slugs, freshwater shrimp, land crabs and frogs can become infected by ingesting their feces, which contains the worm larvae.

Most of the victims infected during this cycle have required hospitalization as the disease affects the brain and spinal cord and can cause a rare type of meningitis. According to Health Department officials, symptoms start one to three weeks after exposure and can last for up to eight weeks.

Health officials advise the public to:

>> Carefully store, inspect and wash produce, especially leafy greens.

>> Always store food in covered containers, wash all produce thoroughly and supervise young children playing outdoors to prevent them from putting snails or slugs into their mouths.

>> Take precautions to control slugs, snails, and rats around properties, and especially around home gardens.

They said symptoms of rat lungworm can vary but include severe headaches and neck stiffness, while the most severe cases can involve neurological problems, pain and disability. Anyone who suffers headaches, fever, stiff neck, tingling or painful feelings in the skin or extremities should seek medical attention, health officials advise.

None of the 11 most recent patients have died. However, state health officials have said there have been two rat lungworm-related deaths since 2007.

Rat lungworm factsheet by Honolulu Star-Advertiser on Scribd