Health officials are urging those who may have been exposed on those dates to take immediate action by getting an immune globulin shot or a hepatitis A vaccine.
"This alert is going out to those patrons who were at Jerry's Deli only in the Westwood side that only ate hot or cold sandwiches," said Dr. Laurene Mascola of the Los Angeles County Department of Public Health.
Mascola said action has to be taken within two weeks of exposure.
The Health Department said the infected employee also worked on Nov. 12-17 but at this point it is too late for those who may have been exposed to be treated.
Hepatitis A is relatively easy to recover from, but it may be weeks before any infected customers to show the symptoms, like nausea and fever.
So far, the Health Department has not gotten any reports about exposures.
"I'm very concerned," said customer Brandon Ceballos. "I'm probably going to go get tested or something. It's freaky."