LOS ANGELES -- Los Angeles County has a hepatitis A outbreak based on two "community-acquired" cases that cannot be traced back to San Diego or Santa Cruz counties, health officials reported Tuesday.

"We are in the situation of a hepatitis A outbreak as of this morning," Public Health Department Director Barbara Ferrer told the L.A. County Board of Supervisors.

Most cases to date have been identified in patients who are homeless or drug users, but include workers at a health care facility working with those patients, the county director of public health said in a news conference.

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Ferrer urged anyone working with individuals at high risk of contracting the disease -- including health care providers, food-service workers and shelter employees -- to get vaccinated.

CBS Los Angeles reports that San Diego County officials earlier this month declared a public health emergency because of the liver disease outbreak that has killed 16 people and hospitalized 300 more since November. Their homeless population has been hit the hardest.

In Santa Cruz County, at least 69 people have been diagnosed with hepatitis A amid a smaller outbreak that broke out in April, according to the San Diego Union Tribune.

"The reason we're particularly concerned (now) is because we have an outbreak in San Diego and we have an outbreak in Santa Cruz, and the contagion is in a population not easily contained," said Dr. Sharon Balter, the chief of the department's communicable disease control program.

The county typically sees about 40 to 60 cases of hepatitis A annually from the population at large, with a concentration often found among food-service workers. But those patients can be readily tracked and follow-up can be scheduled by phone or email, something that's not possible when patients are living on the street.

The virus was identified in a street fruit vendor in Lancaster, LACDPH announced Sept. 4. Anyone who brought fruit from the vendor could have been exposed, CBS Los Angeles reports.

Hepatitis A is transmitted fecal-orally, person to person or through other items such as food, health officials said. Symptoms of acute hepatitis A include fever, malaise, dark urine, anorexia, nausea and abdominal discomfort, followed by jaundice.

County health officials emphasized Tuesday that getting the hepatitis A vaccine is the best protection. Children have been routinely vaccinated since 1999. But many adults lack protection against the virus.

"The safest thing you can do if you work with a high-risk population or if you are worried, is to get vaccinated," Ferrer said.