A recall issued for several varieties of potato chips has been upgraded to the FDA's highest risk level over fears the products are contaminated with a life-threatening bacteria. Utz Quality Foods, LLC issued a voluntary recall in the US of certain varieties of Zapp's and Dirty potato chips in May after Utz learned that a seasoning used in the chips containing dry milk powder may contain the bacteria salmonella. The dry milk powder was sourced from California Dairies, Inc. and supplied by an unspecified third-party vendor. Last week, the FDA then upgraded the recall and classified it as a Class I, indicating 'a situation in which there is a reasonable probability that the use of or exposure to a violative product will cause serious adverse health consequences or death.'

The recall upgrade applies to more than 684,000 chip bags, including: 1.5-ounce plastic bags of Zapp's Bayou Blackened Ranch Kettle Chips; 2.5- and 8-ounce plastic bags of Zapp's Bayou Blackened Ranch Potato Chips; 1.5- and 2-ounce plastic bags of Dirty Brand Salt and Vinegar Potato Chips; 2-ounce plastic bags of Dirty Maui Onion Chip; 1.5- and 8-ounce plastic bags of Zapp's Big Cheezy Potato Chips; and 2-ounce plastic bags of Dirty Sour Cream and Onion Potato Chips. In the original recall notice, Utz said the affected seasoning batches tested negative for the bacteria prior to use, but the company was still initiating the recall 'out of an abundance of caution.'

The products were distributed to retail stores in nearly three dozen states across the country. Salmonella is among the leading causes of foodborne illness in the US, infecting about 1.35 million people every year, the CDC estimates, and leads to 26,500 hospitalizations and 420 deaths. No illnesses had been reported in connection to the original recall in May and an update on any potentially related illnesses has not been given. The original recall applied to nine Utz products: 1.5-, 2.5- and 8-ounce Zapp's Brand Bayou Blackened Ranch Potato Chips; 2-ounce Dirty Brand Salt and Vinegar Potato Chips; 1.5-ounce Zapp's Brand Salt and Vinegar Potato Chips (60 count); 2-ounce Dirty Brand Maui Onion Potato Chip; 2.5- and 8-ounce Zapp's Brand Big Cheezy Potato Chip; and 2-ounce Dirty Brand Sour Cream and Onion Potato Chips.

Symptoms of salmonella appear within eight to 72 hours of an infection, and include diarrhea, stomach cramps, fever, nausea and vomiting. In some cases, however, no symptoms appear at all. Doctors say that warning signs of the infection generally last a few days to a week and that most patients do not need to see a doctor. However, they warn that infants, young children, pregnant women and older adults are particularly at risk from salmonella because they have a weaker immune system. Most people infected with Salmonella recover within a week without treatment, but severe cases may require hospitalization. In serious cases, the bacteria can spread from the intestines into the blood and infect other organs, such as the brain, heart or lungs, which can trigger the potentially fatal complication sepsis. Doctors may attempt to treat the infection in these cases using antibiotics. Health officials urge anyone who develops symptoms to contact their healthcare provider and report the illness to their state health department. Officials urge people who have purchased the affected products to not eat them and immediately discard of them.