Initially , authorities suspected a connection to powdered infant formula . Tests so far have not found contamination in formula , Dr. Van Tauxe said . Wal - Mart has removed a brand of formula from its shelves . He said CDC labs will compare samples of the bacteria from both states in an effort to determine if they came from the same source . Only four to six cases of this type of infection are reported per year .
Initially , authorities suspected a connection to powdered infant formula . Tests so far have not found contamination in formula , Dr. Van Tauxe said . Wal - Mart has removed a brand of formula from its shelves . Only four to six cases of this type of infection are reported per year .