Hawaii Tribune-Herald reported Friday the cases are disturbing because the disease is usually found during the winter season.

East Hawaii epidemiological specialist Marlena Dixon says rat lungworm is a parasite that causes a rare form of meningitis and is difficult to diagnose because of a wide array of symptoms.

Symptoms can include severe headaches, nausea, vomiting, neck stiffness and numbness.

In a severe 2009 case former Big Island resident Graham McCumber spent three months in a coma.

Dixon says the disease can be contracted when people mistakenly eat small slugs on the surface of leafy green vegetables.

Slugs and snails become carriers when they eat feces of rats carrying the parasite.