As the state grapples with the worst outbreak of hepatitis A in nearly two decades — closing in on 100 cases — the public should take some comfort in knowing that the state has concentrated its efforts and manpower in the intense investigation to discover the source.

Even so, the search is extremely difficult, so the public needs to be extra scrupulous about its hygiene habits to help curb the virus.

While the steady increase in the number of cases might cause alarm, the outbreak is not yet close to becoming a public health emergency, the state Department of Health said.

There have been 93 confirmed cases of the viral liver infection as of July 26 — all adults, with 29 requiring hospitalization. The first victim fell ill on June 12.

Although the source of the outbreak has so far eluded health officials, luckily, investigators have been able to focus solely on the hepatitis A investigation.

“Fortunately the dengue (fever) outbreak ended,” said Danette Wong Tomiyasu, deputy director for health resources administration. “Right now we seem to be OK with staffing. Should anything else happen, we’d be struggling.”

Such an investigation can be like finding a needle in a haystack, especially since the source of hepatitis A is usually traced to contaminated food or water.

So far, at least a few food service workers have become infected.

Although the source has not been tied to those establishments, it has prompted alerts for customers who have consumed products there. The latest was from Costco, which contacted 2,700 customers after a report that a bakery worker at the Hawaii Kai location was among the cases.

The state Health Department recommends that those who might have consumed products at those establishments during specific time frames seek advice from their physicians. Vaccination and thorough handwashing are among the best ways to prevent further spread of hepatitis A, health officials said.

Viral particles are shed in the feces of infected people, and a tiny trace is sufficient to spread hepatitis A, which makes it critical for people to wash their hands after using the toilet or changing a diaper, and before handling food.

The process of finding the source can be painstakingly long.

A two-year outbreak in Europe, for instance, has not yet been solved, said Dr. Melissa Viray, deputy state epidemiologist.

Locally, state investigators start with a lengthy questionnaire, interviewing those infected for about an hour and a half.

Their responses are entered into an electronic database in order to find some commonalities. From there, investigators look for signals that lead them to a certain geographic area, food distributor or other link.

They even ask for data from patients’ frequent- shopper cards to note what food products they have purchased.

Unfortunately, hepatitis A has a long incubation period of between 15 and 50 days after exposure, making it all the more challenging to determine the source.

In Beaver County, Pa., a 2003 hepatitis A outbreak infected 527 Pennsylvania residents and another 74 out-of-state residents that eventually was linked to green onions used in the mild salsa served at a restaurant. Those green onions were shipped from northern Mexico.

With so much of Hawaii’s food shipped in, it makes DOH’s investigation even more difficult.

“What we’re looking for is that one potential culprit,” Viray said.