With the number of hepatitis A cases on Oahu climbing to 52 adults, state health officials are urging all residents to consider getting vaccinated — and especially anyone who consumed food or drinks at a Waipahu ice cream shop between June 17 and July 3.

The state Health Department said Tuesday that it is investigating a confirmed case of hepatitis A in an employee of a Baskin-Robbins at the Waikele Center.

Anyone who ordered food or drink at the store on certain days between June 17 and July 3 — days when the employee was working — may have been exposed to the virus and should contact their health care provider about the possibility of receiving a hepatitis A vaccine or an immune globulin, which could provide some protection against the disease if administered within the first two weeks after exposure, officials said.

State epidemiologist Dr. Sarah Park said the Baskin-Robbins store is not the source of the outbreak, but merely a place where one of the victims was employed.

The employee could have been meticulous about cleanliness, and store policies could be in place to prevent the spread of any viruses, Park said. But mistakes do happen.

“The likelihood (that anyone who patronized the store contracted the disease) is very low, but we have to do our due diligence to prevent a second outbreak,” she said.

The employee worked at the store on June 17-19, 21-22, 25, 27, 30 and on July 1 and 3, officials said.

Meanwhile, Health Department investigators continue to interview patients in search of clues that will reveal a source of the cluster of cases, the worst outbreak of hepatitis A in at least a decade, stretching back to when children started getting vaccinated for the disease here in 2006.

Hepatitis A is a contagious liver infection caused by the hepatitis A virus, which is found in the stool of people and is spread by eating contaminated food or drinking water and sometimes through personal or sexual contact. Household members are especially susceptible.

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

Victims usually experience a mild illness lasting one or two weeks but might experience a severe illness lasting a couple of months or more. Most people will recover without complications.

While the disease is rare in the U.S., with fewer than 20,000 cases per year, the risk of an outbreak increases in areas with poor sanitary conditions. A 1988 epidemic in Shanghai, linked to raw clams, affected nearly 300,000 people, according to the World Health Organization.

Park said the problem with finding the disease’s source is that the symptoms don’t appear until two weeks to as long as 50 days after exposure to the hepatitis A virus. The average length of time for the symptoms to appear is 30 days.

“Try to remember everything you ate or drank for a month,” she said.

Park said health investigators are doing their best to compare vast food histories that are often fuzzy at best. “That’s the insanity we’re in right now,” she said.

Park discounted early reports that poke was the source of the outbreak. At the same time, she said cooking food thoroughly can help prevent infection.

“Anytime you eat raw fish, you put yourself at risk,” she said.

The state Department of Health issued a medical advisory to all health care providers June 30, urging them to report all suspected hepatitis A infections immediately.

Of the 52 cases being investigated now, 16 have required hospitalization — all have recovered or are now recovering, Park said.

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

Park urged anyone and everyone to consider getting the hepatitis A vaccination, which is available at local pharmacies. Only two doses of hepatitis A vaccine, given at least six months apart, are needed for lasting protection.

For a list of vaccinating pharmacies, visit 808ne.ws/29l6l7D or call the Aloha United Way information and referral line at 211. Calling ahead for vaccine availability is advised.

While vaccination provides the best protection, frequent hand-washing with soap and warm water after using the bathroom and changing a diaper, and before preparing food can help prevent the spread of hepatitis A, officials said.