As officials scramble to stop a growing listeria outbreak from contaminated cantaloupes, a supermarket chain has also found the bacteria in spinach dip.

Publix Supermarkets issued a voluntary recall on Wednesday for one batch of spinach dip, which was sold prepackaged in 16-ounce containers, with a UPC of 41415-00062 and a use-by date of Oct. 10. The contaminated dip was only sold at Publix stores.

Publix said it discovered the contamination through routine testing. No cases of listeriosis connected to the spinach dip have been reported, but the incubation period between when a person consumes food contaminated with listeria and when they start showing symptoms can be up to two months.

Spinach has been a culprit in several outbreaks of E. coli, but listeria is a less common contaminant, as it is more often found in processed meat or unpasteurized dairy products. E. coli outbreaks tend to affect more people, but listeria is deadlier in the people it does infect. With intensive treatment, E. coli has a mortality rate of less than 10 percent, but the rate for listeria can be up to 20 percent.

The listeria-contaminated cantaloupes have sickened 72 people so far and killed between 13 and 16, making it the worst outbreak of food-borne illness in the United States in more than a decade. The spinach dip seems to pose less of a threat, because it was contained to one chain of stores and the affected products are easily identifiable by their UPC number. The cantaloupes, on the other hand, are unidentifiable if they don't have a sticker identifying their source.

Early symptoms of listeriosis include fever, muscle aches, nausea, vomiting and diarrhea. In most people, the symptoms are mild, but elderly individuals and people with compromised immune systems are at risk of more serious illness. If the infection spreads to the nervous system, it can cause meningitis, with symptoms of headache, stiff neck, confusion, convulsions and sometimes death.