Escherichia coli O157:H7 in Feral Swine near Spinach Fields and Cattle, Central California Coast

Recent experimental and epidemiologic studies suggest that domestic pigs are biologically competent hosts and a potential reservoir of Escherichia coli O157:H7 (1,2). Cattle are considered the primary reservoir of E. coli O157, but fecal shedding by other domestic livestock and wildlife has been described (3,4). E. coli O157 was isolated from a wild boar in Sweden, but there is limited information on its occurrence in feral swine in the United States (5). We report findings from an environmental and laboratory investigation after a nationwide spinach-associated outbreak of E. coli O157 in which the outbreak strain was isolated from feral swine and other environmental samples.