Health officials in San Mateo County say that while the cause of a salmonella outbreak in the county last month remains under investigation, almonds have been ruled out as the source.

The outbreak, which was traced back to La Tapatia restaurant in South San Francisco, affected 22 people including one restaurant employee, according to San Mateo County Health Services spokeswoman Beverly Thames.

In a communicable disease report issued to the Board of Supervisors, county health officials initially leaned toward almonds as the cause, saying specimens from the restaurant patrons matched a strain of salmonella found in raw almonds.

However, Thames said Wednesday evening that it appears the salmonella originated elsewhere. Testing to determine the source of the bacteria is ongoing.