It doesn't happen often, but food does get contaminated from time to time.
A shopper went to a Southwest Walmart and purchased a 5 oz. bag of Fresh Express Organic Marketside Spring Mix (production code G089B19, best-if-used-by APR 14) to make a salad. They found deteriorated bat remains in the salad mix. Now a couple has been advised to receive rabies postexposure prophylaxis treatments. The product has been recalled.
PositiveTip: Always pay close attention to any suspicious objects in your food--especially if you did not. prepare it yourself!