The nine people have been involved in six separate cases of staphyloccocal intoxication, an acute gastroinstestinal illness characterized by a sudden onset of vomiting, usually followed by diarrhea, according to the State Health Department.

There is no fever and symptoms are usually resolved in a day. Most of the people affected from the Maui cases have been children ages 3 to 9.

The Spam musubi was purchased from four or five different vendors, Health Department spokeswoman Janice Okubo said. Health Department investigators believe that consumer mishandling without proper refrigeration may have caused some of the illnesses.

The Health Department is reminding vendors on Maui about requirements to keep warm foods heated above 140 degrees or cold foods refrigerated below 45 degrees.

The department also is warning consumers that Spam musubi and other foods such as bentos are highly perishable and should be eaten within four hours of preparation — including time for preparation, transportation and storage.

Perishable foods that have been displayed at room temperature should be eaten immediately and should not be refrigerated because bacteria could multiply and cause illness.

The most Spam musubi cases follow two or three cases incidents of Spam musubi food poisoning on Maui in November, Okubo said.