SAN JOSE -- Santa Clara County health officials issued a warning Thursday to customers of a San Jose Jamba Juice who may have been exposed to Hepatitis A.

At an afternoon news conference, Santa Clara County health officials said a worker at the popular Willow Glen neighborhood smoothie store, located at 1140 Lincoln Ave., was diagnosed Wednesday with the virus.

"It's not that she did something wrong or the store did something wrong," said Dr. Sara Cody of the Santa Clara County Public Health Deparmtent. "It's that people shed the Hepatitis A virus in their stool before they even have symptoms so she had no idea she was infectious while working."

Health officials said anyone who visited the store on the following dates may have been exposed -- Aug. 1, 2, 3, 6, 7, 8, 9, 11, 13, 14, 15, and 16. Health officials recommended vaccinations for anyone who visited the store between Aug. 9 and 16.

For those who visited Aug. 9 or before, health officials recommended they be aware of symptoms and should any appear to contact a health provider. After 14 days the vaccine is no longer good to prevent the disease.

The vaccine is harmless, officials said, and recommended for people 1 year to 40 years old. For anyone who ate at the store and is over 40 years old, under 12 months old, immune compromised, with chronic liver disease, or pregnant, immune globulin is available for prevention of infection.

Symptoms of Hepatitis A are jaundice, fatigue, abdominal pain, loss of appetite, nausea, diarrhea and fever. Symptoms appear anywhere from 14 days to 50 days after exposure and can last less than two months or as long as six.

Once contracted there is no cure for the disease but it does eventually pass. Health officials said the worker appears to have been very hygienic and the chance of infection for customers appears to be very small, but they are required to be cautious.

"I just want to emphasize how unusual this is for us," Cody said.

There are usually about 25 cases a year in the county and only six so far this year, she said. The number of cases was declining due largely to widespread vaccination.

Those that have had a Hepatitis A vaccine or who have already had the disease are immune, Cody said.

The Jamba Juice store was closed and cleaned and all stock has been replaced, Cody said. She said it is the person, not the place that is infected.

The most effective weapon against Hepatitis A is thoroughly washing hands after trips to the restroom.