The Hawaii Kai Costco is alerting some 2,700 customers after a worker in the store’s bakery came down with hepatitis A, the state Department of Health confirmed Thursday.

Costco is notifying anyone who bought baked goods from June 16 to 20 to let them know they might have been exposed to the disease.

The employee is the latest food service worker and one of 93 people who have contracted hepatitis A in Hawaii’s worst outbreak of the disease in nearly two decades. Health officials previously identified stricken employees of three other food establishments.

State epidemiologist Dr. Sarah Park said that although it’s unlikely customers of Costco have become infected, anyone who consumed products from the bakery on those dates should contact their health care provider for advice and possible preventive care, including a possible hepatitis A vaccination or immune globulin to help protect against the disease.

Park said the Health Department didn’t issue a formal alert itself because Costco, with its membership retail structure, is able to contact all the customers who bought items from the bakery on those dates and volunteered to do so.

Keith Nomura, the store’s general manager, said the bakery employee was on vacation when he contracted the disease and worked only three days, from June 16-18.

But since products made June 18 can be sold for another two days, the company decided to contact customers who bought items made and packaged in the store over the five-day period, said Gail Ogawa of the state Disease Outbreak Control Division.

Nomura said that when the company was contacted by the Health Department a few days ago, it didn’t hesitate to do its part to alert customers with both a phone call and a letter starting Thursday.

“Food safety is second to none at Costco,” he said. “We go above and beyond what’s required. Costco has a strict policy of no-barehand contact with the food. Our employees always wear gloves.”

He added that the employee has recovered and been cleared to go back to work.

Park said she appreciates Costco’s willingness to alert customers on its own, because otherwise the task would fall to the state.

Meanwhile the Health Department continues to search for the source of the outbreak, with more than 30 staff members helping out, according to Park.

While health investigators so far have been frustrated in part because the symptoms don’t appear for 15 to 50 days after exposure, the newest “outlier cases” on the neighbor islands — where the victims spent only a few days on Oahu — are starting to help scientists better focus, Park said.

The epidemiologist said she’s hopeful some kind of breakthrough might even occur in the next few weeks.

“We think we’re making progress,” she said. “We’re hopeful there’s a light at the end of the tunnel, but it’s not bright enough for our liking yet.”

So far, nearly one-third of the 93 victims — 29 — have required hospitalization. The onset of symptoms for the earliest victims was June 12, and the most recent is July 19.

Symptoms of hepatitis A infection include fever, fatigue, loss of appetite, abdominal pain, dark urine, diarrhea and yellow skin and eyes.

Specimens sent to the Centers for Disease Control and Prevention indicate that Hawaii is dealing with a viral strain that appears to be unique to the islands, officials said.

Other food service employees who have come down with the disease include workers at Baskin- Robbins at the Waikele Center, Taco Bell in Waipio and Sushi Shiono at the Waikoloa Beach Resort on Hawaii island.

Anyone exhibiting symptoms of hepatitis A, especially food service employees, should stay home and contact their health care provider, officials said.

The hepatitis A vaccination is available at local pharmacies. Two doses of the vaccine, given at least six months apart, provides lasting protection.

Health officials say that while a vaccination provides the best protection against the disease, hand-washing with soap and warm water after using the bathroom or changing a diaper, and before preparing food, can help prevent the spread of hepatitis A. Thoroughly cooking food can also help prevent infection.

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