The worst hepatitis A outbreak in nearly two decades has now infected 93 adults in the Aloha State, including a worker at Sushi Shiono Waikoloa on Hawaii island who recently visited Oahu.

It was the first time that a food service employee on the grounds of a tourist resort — the Waikoloa Beach Resort, in this case — had fallen ill in the current rash of cases. But health officials emphasized that the sushi restaurant and catering business is not the source of the outbreak. And the likelihood of transmission there is very low.

Still, they urged anyone who consumed food or drink from Sushi Shiono recently to contact their health care provider about getting the hepatitis A vaccine or immune globulin to help protect against the disease. The dates of possible exposure are July 5-8, 11-15 and 18-21.

“It’s important for anyone who thinks they might have been exposed to hepatitis A talk to their doctor about vaccination,” said Dr. Melissa Viray, deputy state epidemiologist. “Be aware of symptoms, including fever, loss of appetite, nausea, abdominal pain, dark urine, light stool, yellow skin.”

The viral liver infection can be spread through contaminated food or drink, fresh or frozen, or through close personal contact. The vaccine can prevent infection if administered within two weeks of exposure.

Tracing the source of this outbreak is a daunting task because symptoms don’t appear for 15 to 50 days after exposure. Despite focused effort, the virus has confounded the disease detectives at the Department of Health.

“People are definitely putting in a lot of time, devoting a lot of man-hours,” Viray said Tuesday. “It’s extraordinarily frustrating. Hepatitis A is incredibly frustrating.

“Our interest is twofold: to try to find the culprit so we can eliminate it if it is still in the food supply or the environment, and to identify cases so we can prevent any secondary cases from those individuals.”

Specimens sent to the Centers for Disease Control and Prevention were found to be one viral strain that is not in the national bank and appears to be unique to Hawaii.

The department has nine investigators tackling the current outbreak, plus other staff helping with data entry, following up with contacts of cases, and doing education and communication, according to Gail Ogawa, a public health educator at the Disease Outbreak Control Division.

Investigators interview victims using an extensive questionnaire whose results go into a database that is used to generate commonalities between the cases, Viray said. They also contact retailers so they can comb through records from shopper cards offered by patients.

“Above and beyond retailers, we see if there are distributors in common, which could help explain why the outbreak is so widespread,” Viray said.

The outbreak has taken a heavy toll. Out of the 93 victims, 29 have required hospitalization. Over the past decade there has been an average of just 10 hepatitis A cases a year in Hawaii.

All the victims are adults who were exposed to the disease on Oahu. But four of them live on Maui, Hawaii island and Kauai.

The first neighbor islanders to fall ill had stayed on Oahu for months. But the more recent ones were here for a matter of days, which should make it it easier to track their movements on the island.

“These outliers with finite exposures, we’re taking a very close look at what they’ve done, where they went, what they ate, what they drank, to see if that might help break this open,” Viray said.

The first victim fell ill June 12, and the most recent on July 19. Most people recover on their own, but in rare cases hepatitis A can cause liver failure.

Viral particles are shed in the feces of infected people, and a tiny trace is sufficient to spread it. Thorough hand-washing is crucial after using the toilet or changing a diaper, and before handling food.

Two other food service workers, at Taco Bell in Waipio and Baskin-Robbins at Waikele Center, also came down with the disease earlier, but there is no evidence they transmitted it to customers.

Seattle attorney Bill Marler, who specializes in food safety, urged people who contracted hepatitis A to offer the Health Department wide access to their records.

“I think the public needs to help the Health Department by giving them the information that would allow them to really bore in on not just what people ate, but where they were, what did they do, who did they come in contact with,” Marler said.

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