State officials issued a public health alert Monday about a potential outbreak of hepatitis A, in response to a church supper in Durham at which food was served by a volunteer who was unaware she was infected.

The Maine Center for Disease Control and Prevention worked Sunday with leaders of a Quaker congregation, the Durham Friends Meetinghouse, to notify about 100 people who attended the supper Sept. 28 of their potential exposure to hepatitis A. Because the public was invited to the supper, state officials said they cannot be sure that everyone has been notified.

No sickness has been reported, but the CDC is taking precautions, officials said, including setting up a vaccination clinic. The CDC will host a free clinic from 1 to 4 p.m. Wednesday at the Durham Eureka Community Center, at 605 Hallowell Road.

“We don’t know that it’s spread, but we do know that there’s a risk,” said Dr. Sheila Pinette, director of the Maine CDC. “There is a two-week period after the event where people can be protected with vaccinations.”

Hepatitis A, which affects the liver, causes symptoms such as abdominal pain, fatigue, nausea, vomiting, diarrhea, dark urine and jaundice. Pinette said many people fall ill from hepatitis A, recover and don’t realize that they had the disease. She said the symptoms sometimes are so mild that people just feel tired for a day.

Although most children are now vaccinated for hepatitis A, the vaccine wasn’t widely used until a few years ago, Pinette said, so most adults are not vaccinated.

The CDC is urging people who attended the church supper and aren’t vaccinated to get the vaccine by this coming Saturday – two weeks after the supper.

Pinette said a church volunteer who did not know she was infected with the virus prepared food at the supper in Durham, which is about 10 miles east of Brunswick. When the volunteer later became ill, she was diagnosed with hepatitis A, Pinette said.

Hepatitis A cannot be spread through casual contact, but is often spread through contaminated food. The risk from the church supper has nothing to do with undercooked food or unsanitary conditions, Pinette said.

The infected volunteer also prepared food for preschool children weeks earlier, but in that case the two-week vaccination period is over, Pinette said, so nothing can be done other than to watch for symptoms.

Church officials could not be reached for comment Monday.

People who fall ill from hepatitis A respond well to treatment, Pinette said, so those who were exposed should visit their doctors if they get sick.

John Martins, spokesman for the Maine Department of Health and Human Services, said Maine typically has about seven cases of hepatitis A per year. A potential outbreak in which people beyond those immediately involved have to be notified occurs only about once every two years, he said.

Nationally, the latest major hepatitis A outbreak occurred this spring, when 162 people were infected and 71 were hospitalized after eating Townsend Farms organic frozen berries. The outbreak was mostly in western states, including Arizona, California and Colorado. Townsend Farms recalled the products.

Joe Lawlor can be contacted at 791-6376 or at:jlawlor@pressherald.comjlawlor@pressherald.comTwitter: @joelawlorph@joelawlorph