Five adults in Hawaii have been diagnosed with hepatitis A after eating Townsend Farms frozen berries that were sold by Costco, and the retailer is offering free vaccines to customers who bought a recalled organic berry mix.

Townsend Farms Organic Antioxidant Blend berry mix has been implicated in a multistate outbreak of hepatitis A, a contagious liver infection that can cause mild to severe illness. The Oregon fruit distributor recalled the product after learning that one of the ingredients, pomegranate seeds from Turkey, could be linked to illness.

In Hawaii, four of the adults who came down with hepatitis A last month had eaten the recalled organic berries, according to Dr. Sarah Park, state epidemiologist. Three lived on Oahu and one on Kauai. The fifth person, a Hawaii island resident, had eaten a different Townsend Farms frozen berry mix that was not organic, and the state Health Department is trying to determine whether the berries or something else caused his illness.

“In the meantime he is considered a probable case,” Park said Friday, adding that people should not assume it was the berries.

Another four cases of hepatitis A were recently identified through the state Health Department’s monitoring system, and investigators are tracking down the affected people to try to determine how they might have contracted the disease and whether they too ate frozen berries, she said.

“The four we are investigating, we know they have hepatitis A, but we don’t know their exposure,” she said.

Hepatitis A is usually spread through contaminated food or drinking water, and can also be spread through close personal contact with an infected person. The hepatitis A vaccination can prevent the illness if given within two weeks of exposure.

“The big message for folks out there is if you have eaten the product within the past two weeks, go see your medical provider,” Park said.

Typically the number of hepatitis A cases in Hawaii ranges “from the teens to the 20s” each year, Park said.

The disease can range from a mild illness lasting a few weeks to serious illness lasting several months. Symptoms include fatigue, stomach pain, fever, loss of appetite, jaundice and dark urine. People with symptoms should see their medical providers promptly.

At Costco outlets on Oahu, pharmacists said Friday they had been deluged by calls from customers and people coming in for the vaccine. The chain is offering free vaccines to people who bought and consumed the berries implicated in the outbreak. The vaccine normally costs $80.

“We recommend that if they would like to have the vaccine, they call ahead and make an appointment,” said a pharmacy technician at the Costco in Iwilei. “For the ones who are walking in, we are trying to accommodate them as best we can. Actually, we have been bombarded with them.”

Children in Hawaii have been routinely vaccinated against the disease since 2006, and some adults who travel to developing countries also get the vaccine. The disease is tied to poor hygiene and spread through fecal-oral contact, Park said.

“A lot of our kids, as long as they have been getting their vaccines, are immune,” Park said. “If you look nationally, among all these states that have cases, I think there has been one reported child case confirmed. I think it’s really a great testament to the benefit of vaccines.”

Those who contracted hepatitis A in the current outbreak in Hawaii ranged in age from 19 to 62, she said, and all have recovered.

“They are all doing fine now,” Park said. “There was only one that required hospitalization, and it was very brief.”

Waikiki resident Hollie Lambert, 20, said she had eaten plenty of the Townsend Farms organic frozen berry blend last month, but there is none in her freezer right now and she has no plans to get vaccinated.

“I put them in smoothies and on oatmeal,” she said. “It doesn’t affect my opinion of the brand. It’s very random and could happen to anything. I’m a little wary of vaccines. I think I’m going to take my chances.”

As of Friday, 79 people in eight states had contracted acute hepatitis A infections that may be linked to consumption of the product, according to the Centers for Disease Control. Thirty were hospitalized.

“I am concerned that in the coming months we may still see cases,” Park said. “The health care providers need to be especially alert, and persons out there should realize that if I am starting to feel under the weather and I turn yellow and my urine is dark, maybe I should see my medical provider sooner rather than later.”