Nacho cheese sauce is the likely suspect in a botulism outbreak among patrons of a gas station in California, according to public health officials in Sacramento County.

In addition to narrowing the scope of possible sources, the Sacramento County Public Health Department announced Wednesday that another patient with suspected foodborne botulism has been added to the outbreak list.

Five other people are hospitalized and in serious condition with confirmed botulism poisoning. Four of them reported eating “prepared food” from the Valley Oak Food and Fuel gas station in Walnut Grove before becoming ill.

“Persons who consumed prepared food, particularly nacho cheese sauce, from Valley Oak Food and Fuel gas station from April 23 through May 5 and have symptoms should contact their medical provider immediately,” according to the Wednesday update from the county.

“Botulism is a rare but serious paralytic illness caused by a nerve toxin that is produced by the bacterium Clostridium botulinum. Symptoms can include double vision, blurred vision, drooping eyelids, slurred speech, difficulty swallowing, dry mouth, and muscle weakness.”

The county’s Department of Environmental Management ordered the gas station to stop selling “prepared food” on May 5 after the health department alerted other officials of the outbreak connection.

Food safety attorney Bill Marler said the situation is troubling because it likely involves a canned or jarred product.

“If it’s commercially manufacturer it could be in use in other places,” Marler said Wednesday.

Sacramento County officials did not specify whether the nacho cheese sauce at the gas station was made on site. It could be a situation where the gas station employees used cans or jars from the location’s retail stock, which likely means the contaminated product was distributed elsewhere.

Editor’s note: Bill Marler, founding member of MarlerClark LLP in Seattle, is publisher of Food Safety News.