The California Department of Public Health (CDPH) released a statement
Monday indicating the cheese sauce had tested positive for the toxins released by bacteria that cause the illness. The same toxins were identified in patients tested by the department.
The CDPH said it doesn't believe there is any continued threat to the public because the contaminated sauce was removed from sale on May 5.
Botulism is a rare illness caused by nerve toxins released by bacteria called Clostridium botulinum, according to the Centers for Disease Control and Prevention. Symptoms can include blurred vision, drooping eyelids, slurred speech and paralysis, among others. Some cases can be fatal.
CNN affiliate KTXL reports that one woman, Lavinia Kelly, was reportedly hospitalized after putting the nacho cheese sauce on some Doritos chips on April 21.
"My phone rings and I pick up the phone and it's her, and she can't articulate a word," her sister, Theresa Kelly, told KTXL. She said that at first she thought her sister was going to die.
Kelly has spent more than three weeks in intensive care, KTXL reports.
California's Department of Public Health and local health departments have asked health providers in the area to be aware of the symptoms of botulism, according to their release.
CDPH Director and State Public Health Officer Dr. Karen Smith also stressed the importance of looking out for the potential risk of foodborne illnesses as barbecue season begins this summer.
"While there are still unanswered questions about this outbreak, these tragic illnesses are important reminders to be vigilant about food safety," she said in the statement.
Though the store was ordered to stop selling prepared foods on May 5, it was allowed to reopen and sell prepackaged food items only on May 8 after a California Department of Public Health officer seized four bags of the cheese sauce, according to a Sacramento County inspection report.
Botulism outbreaks are rare, according to the CDC's website
Foodborne botulism is spread through ingesting contaminated foods, the CDC said. The toxins that cause the illness can be found in foods that are not properly processed or stored and they cannot be identified by the naked eye, states the CDPH.
Symptoms typically begin to appear around 18 to 36 hours after eating the food.
While botulism can be fatal, the CDC's website said only 3%-5% of patients die.